Furore entered the English language by the end of the 18th century to refer to a “wave of enthusiastic admiration”:

1790, Italian form of furor, borrowed into English originally in the sense "enthusiastic popular admiration;"

but over time this meaning was eventually lost:

it later descended to mean the same thing as furor and lost its usefulness.

(Etymonline)

(As a side note, the Italian term furore doesn’t have and never had the connotation with which it was originally adopted by the English language.)

According to Google Books, from the ‘50s the term appears to be still commonly used in BrE, while less so in AmE.

Questions:

  1. What (a book, a play etc.) made “furore” a term adopted by the English language in the late 18th century with a different connotation from its original one?

  2. When, roughly, did its meaning “enthusiastic popular admiration” start to die out?

  3. Is furore currently used as a close synonym of furor, or does it carry different nuances in BrE and AmE?

Just as a side note, curiously, John Steinbeck's famous "The Grapes of Wrath" is known in the Italian version as FURORE


I puritani hanno fatto furore! (I Puritani was a big hit!)

After the premiere of his opera I puritani at the Comédie Italienne in Paris, 24 Jan. 1835, the composer Vincenzo Bellini wrote to a friend:

«Mi trovo all’apice del contento! Sabato sera è stata la prima rappresentazione dei Puritani: ha fatto furore, che ancora ne sono io stesso sbalordito… Il gaio, il tristo, il robusto dei pezzi, tutto è stato marcato dagli applausi, e che applausi, che applausi».
I am at the peak of happiness! Saturday evening was the first performance of I puritani: it was a sensation (lit. ‘made furor’), which I myself still find astonishing ... The joy, the sadness, the strength of the pieces — all were marked with bursts of applause, and what applause, what applause. — Vincenzo Bellini to Francesco Florimo, 1835.

In Bellini’s day, the theater slang expression fare furore, along with others drawn from the opera and theater, had slowly been making its way into general language use in Italy, where it is still current today. The earliest attestation of the phrase, however, had a completely different meaning:

JABRA Turco, eßendo in Ghetto, faceua un gran furore contro d’uno Hebreo…
In the ghetto, Jabra the Turk committed a serious assault against a Jew. — Anton Francesco Doni, La Zucca (Favola XXI 1), 1565.

Metaphorical violence, insanity, or anger is hardly alien to designations of popularity: consider a smash hit that’s now all the rage among its fan(atic)s who are absolutely crazy for it. In fact, in the early 19th century, if an opera wasn‘t an immediate furore, but was growing in popularity, it could be said to “attack.”

I could not determine from any online source exactly when the theatrical expression arose, but I suspect it was sometime after the mid-17th century dominance of commercial opera houses in Italy, when having a hit production didn’t merely add to fame but also fortune. Opera as popular entertainment was no small industry: Venice alone would boast of eleven opera houses; in Purcell’s London, there were none.

I also doubt —despite Bellini’s mentioning fare furore in the same breath as thunderous applause — that there was much metaphorical or associative force left in the Italian expression beyond a general notion of enthusiastic excitement. The mid-19th century coining of the verb furoreggiare with the identical meaning efficiently removes itself even further from any whiff of frenzied violence.

Many in Bellini’s Paris audience were familiar with the expression in its calqued French version, faire fureur, and that very year, it was defined in the sixth edition of Le Dictionnaire de l'Académie française as “said of a person or thing that is strongly en vogue, that excites in the public a great eagerness, a lively curiosity.”

In 1784, a German writer (Magazin der Musik 2, 563) cites an entire sentence in Italian, “Ma non fece furore” (But he wasn‘t a hit) because he finds the expression so characteristic of opera audiences in Italy and of the Italian mentality in general.The loud, boisterous, and furiously enthusiastic nature of such audiences will play a role in the English use of furore, which, unlike the French and German usage, has more interest in the noun than the entire phrase. Furore machen, however, begins to appear in 1830 as a fully German expression in the works of Heinrich Heine and Hermann von Pückler-Muskau and is still current today — along with its evil Italian twin, fare fiasco, Fiasko (machen), to be a total flop.

England

Despite the early lack of a dedicated opera venue and a resident company that only lasted eight years, England was not an opera wasteland. Travelling companies from Italy or Germany might remain in the country for extended stays, and the sons of aristocrats or wealthy businessmen would encounter opera in France or Italy as part of their “Grand Tour.” Musical journals would also report on productions in Italy and elsewhere.

While the online Etymological Dictionary and others suggest a 1790 appearance of furore in English, I have been unable to verify the date. Given the relative lack of online resources before 1800, that is hardly surprising. The first attestation I was able to find was in a newspaper article — not from a London paper, but Bristol:

The furore which this piece excited, was not confined [to a] few individuals, but was general throughout the whole assembly. — Bristol Mirror, 11 Dec. 1819.

Unlike the German and French expressions, furore appears without the bland causative, the emotional quality enhanced by the verb ‘excite’. The focus is on the enthusiastic response of the audience, efficiently including the applause of Bellini’s letter. This piece of music was surely the hit of the evening, but readers are left with the sounds and motion an audience member would have experienced first hand.

This usage also assumes that enough readers of this Bristol newspaper were both interested in the local cultural scene and knew the word or at least had heard it before. There must be some London history hiding within.

This history becomes more visible in 1824:

... its close was followed by a degree of enthusiastic applause, which raised the idea of an Italian audience tutto furore, ln fact, it was one of the finest instrumental achievements we ever heard in our national Theatres. — Morning Post (London), 15 Oct. 1824.

All was enthusiasm! tutto furore, to use the terms of that expressive language, which seems to have been created for the use of the arts. From the gondolier to the patrician, every body was repeating “Mi rivedrai, ti revedro.” [from Rossini’s Tancredi, 1813] In the very courts of law, the judges were obliged to impose silence on the auditory, who were ceaselessly humming “Ti revedro.” Of this we have been credibly informed by many persons who were witnesses of the singular fact. — Edmund Burke, Annual Register, vol. 66, 1824, 204. Also without last sentence: Entry “Rossini,” A Dictionary of Musicians, 1825 (1824), 385f.

… its close was followed by a degree of enthusiastic applause, which raised the idea of an Italian audience tutto furore, ln fact, it was one of the finest instrumental achievements we ever heard in our national Theatres. — Morning Post (London), 15 Oct. 1824. BNA

The Italian tutto furore ‘all furore’ flatters readers who understand the phrase and, like the earlier German citation, purports to tell the reader about Italian audiences, a memory wealthier readers who had travelled to Italy would savor.

Occasionally, however, there is something similar to the German and French as calques — or semicalques — of the Italian:

GENOA. Since the production of Eliza di Montalieri, we have had Gabriella di Vergy, an opera composed by Mercadante in Spain, but revised by himself here, which created a furore ... — William Ayrton, The Harmonicon 10, 1, (London),1832, 285.

The Harmonicon, a periodical that reported opera and concert news from all over Western Europe, was one vehicle through which furore would become a common expression.

Furore as Chaotic, Out of Control

Not everyone was enthusiastic about enthusiastic opera audiences or Continental singers. Tutto furore could be nothing but sound and fury, unwarranted adulation of mediocrity, and loud, riotous mob behavior:

It is good time for our foreign singing birds, German and Italian, to be on the wing homewards. ... the best of the new old pieces which are served up and received con furore in Italian towns, would hardly linger out a three nights' existence in London: witness, in proof, Maestro VACCAI's Romeo. [London debut, 10 April 1832] ... — The Atlas (London), 5 Aug. 1832. BNA

Or this comparison in a Welsh newspaper of the way the Spanish mezzo-soprano/contralto Maria Malibran was received in Britain and Milan:

MALIBRAN IN MILAN. — The English, after all, are behind many other nations in the art of running mad. We get now and then into a pretty fit of delirium, but it is all over before we can enjoy the real flavour of a furore. …We, however, did something grand when [Maria] Malibran was amongst us. We did call her forward three times in one night, and we are laughed at all over the Continent for our moderation! Observe what they have done at Milan, according to the Gazette Musicale: “The opera was Bellini's Gorma [sic]; during the first act she was called for sixteen times, which exceeds anything of the kind ever heard of on Italian boards. When she re-appeared in the second act the applause was no longer confined to distinct rounds; it was a perfect tempest, … The stamping of feet, clapping of hands, and the roars of Bravo,' interspersed with yells of delight, lasted so long that the chief of the police, who was in the theatre, thought it necessary to restore tranquillity. Vain efforts! For more than a quarter of an hour there was no other performance but that of the audience itself. A superior authority was sent for, and the principal magistrate of the city, after having with difficulty obtained a hearing, declared that if the noisy demonstrations of satisfaction were not suspended, he would be himself bound to cause the evacuation of the theatre, because he could no longer answer for the safety of the building. This was the only means of curbing the enthusiasm of the spectators." — Monmouthshire Merlin (Monmoth), 10 Oct. 1835.

From this description of police having to intervene in what in the English version of the French report was essentially a mob out of control, it does not take a conceptual leap to arrive at the modern British usage, still retaining a vaguely Italian pronunciation /fju:ˈrɔ:rɪ/ for any controversy or dispute. Remember also that the British usage has always focused on the excitement and affect, not the success it indicates:

In 1950 a scientist by the name of Immanuel Velikovsky caused a considerable furore in the historical, religious and astronomical worlds by stating unequivocally that the flooding was caused by Venus which had been wrenched free from Jupiter and made an uncomfortably close encounter with earth. A very scholarly and erudite work, widely acclaimed at the time but since much maligned. — Alistair Maclean, Santorini, London, 1987. BNC

I can't begin to imagine the sort of furore that might break out if judges started to hand out the sort of penalties that they saw fit in particular cases. — Jonathan Cowap Morning Show: radio broadcast (Leisure). Rec. 7 Dec 1993. BNC

Institutional Review Boards (IRBs) are an important link in subject protection program, and their function defines ethical credentials of research. Of late there has been a furore in the country over the number of deaths in clinical research, and allegations of unethical research. — Ravindra B. Ghooi, “Institutional Review Boards: Challenges and Opportunities.” Perspectives in Clinical Research 5.2 (2014), 60–65.

America

The first use of furore in an American newspaper isn’t furore at all, but an italicized furor:

Niblo’s: The Revolving Statues, by the Ravels, the production of which has created quite a furor among artistes, amateurs, connaisseurs, and, in fact, throughout the whole class of visiters to the garden, will be repeated this evening, with other favorite entertainments, in which this popular family will appear. — Morning Herald (New York), 27 July 1839.

Our letters from Paris and London state that she resembles, but is superior to, the celebrated Mademoiselle Rachael, who has created so great a furor in France. — Morning Herald (New York), 27 Aug.1839.

Tomorrow night a new ballet is brought out, and another rush for tickets will be made. We never saw such a furor as now exists to go to the Park Theatre. — Morning Herald (New York), May 21, 1840.

Ordinarily, italic furor would signal the original Latin meaning of unbridled rage, though the meaning here is clearly that of the Italian. This raises the question of whether the Italian three syllables ever penetrated American English beyond a few elites. This would certainly help explain its absence from American dictionaries and its virtual disappearance from American sources.

The Italian spelling, does, however, appear in a bit of newspaper filler in 1842:

At Paris the fashion during hot weather has been that of swimming. … M. Swarmer, taking advantage of this furore, has established cold baths on the Quay d’Orsay, in which he has actually been teaching the fair sex to swim. — Macon Herald (Macon, Miss.), 26 Oct. 1842; Indiana State Sentinel (Indianapolis), 1 Nov.1842.

This is the Italian spelling, but the meaning has been transformed to denote a popular trend, as in this Australian newspaper:

As to the manteau cardinal, it is a perfect furore — the warehouse of Delille, in Paris, is the general rendezvous of the elegantes of Paris, and hardly can they suffice for the orders they receive. This costume is likely to hold for a length of time its vogue, for its expense renders it exclusive. — Launceton Advertiser (Tas.), 20 Oct. 1842, p. 4.

Later, however, the standard “Bellini” meaning appears:

Leon Pillet, the director of the opera, has arrived in Milan, on his voyage of discovery for a tenor and a prima donna. He came in time to witness a dreadful fiasco of Pacini's Opera “Maria” and Taglioni's grand ballet “II patto inernale.” The present Italian composers are so very monotonous and hurdy-gurdy, that Italy, the cradle of music and the opera, is obliged to ask the loan of Robert le Diable, Zampa, Masaniello, and Der Freischutz; the dilettanti dread a little the influence of this “musica ultra montana,” but the public generally are very well satisfied with the change; so Robert has made furore in Trieste, and the Huguenots are, under another title, very much liked in Florence. — The New York Herald, March 06, 1844.

The New York musical world is in a perfect furore on account of the wonderful performances of the great Pianist, just arrived, Mr. Meyer. — Richmond Enquirer 42, 49 (24 Oct. 1845).

The Globe says: Their performances are certainly the most wonderful and pleasing ever submitted to the public, and met with the most decided success. Their dances consist of groupings in figures of classical beauty now resembling baskets of luscious fruit now like clusters of flowers, … Their wonderful and novel performances created quite a furore. Indiana State Sentinel (Indianopolis) 6, No. 28,31 Dec. 1846.

The Danseuses Viennoises have produced quite a furore in our quiet city. — Richmond Enquirer 44, 4 (14 May 1847).

The first decades of the twentieth century saw the virtual disappearance of furore, though one still occasionally finds it, these two in the modern British sense of controversy, brouhaha:

The article quoted Israeli archeologist Ze'ev Herzog of Tel Aviv University as setting off a furore in Israel by stating that stories of the patriarchs are myths and that neither the Exodus nor Joshua's conquests ever occurred. — Jewish Post (Indianapolis), 25 April 2001.

The recent furore regarding HIV in the porn industry has once again brought to the fore the question of safety practices within adult entertainment. Corsair, Volume 100, Number 13, 1 December 2010.


Recent dictionary treatment of 'furor' and 'furore'

Merriam-Webster's Eleventh Collegiate Dictionary (2003) has the following entries for furor and furore:

furor n {MF & L; MF, fr. L, fr. furere to rage} (15c) 1 : an angry or maniacal fit: RAGE 2 : FURY [definition] 4 ["a state of inspired exaltation : FRENZY"] 3 : a fashionable craze : VOGUE 4 a : furious or hectic activity b : an outburst of public excitement or indignation : UPROAR

furore n {It, fr. L furor} (1790) 1 : FUROR 3 {"a fashionable craze : VOGUE"} 2 : FUROR 4b {"an outburst of public excitement or indignation : UPROAR"}

Several things are noteworthy about these entries:

  1. MW traces furor's lineage to Latin via middle French and furore's to Latin via Italian.
  2. It identifies furor as having entered English in the fourteenth century and furore as having Entered English by 1790.
  3. Both definitions of furore that MW lists are particular definitions of furor—that is, furor has five distinct meanings in English, and two of those are the only MW-recognized meanings of furore in English.
  4. None of the definitions listed in the two entries is obsolete, which suggests that the premise in the original question that the meaning "enthusiastic popular admiration" has dropped out of use in English is not valid.

The American Heritage Dictionary of the English Language, fifth edition (2010) generally agrees MW, except that it characterizes furore as a chiefly British variant spelling of furor in two senses of the latter word:

furor n. 1. A general commotion; public disorder or uproar. 2. Violent anger or frenzy. 3. A fashion adopted enthusiastically by the public; a fad. 4. A state of intense excitement or ecstasy.

furore n. Chiefly British Variant of furor (senses 1 ["A general commotion; public disorder or uproar"], 3 ["A fashion adopted enthusiastically by the public; a fad"]).

This agrees in most ways with Merriam-Webster's treatment of the two terms, although it places the "uproar" sense of furor first instead of last chronologically, clouding the question of what the original meaning of furore in English was (AHDEL cites "senses 1, 3" of furor as the meanings of furore, without specifying which sense came first in English).

Neither MW's nor AHDEL's treatment of furor and furore addresses an important etymological question: Dids furore introduce its two current meanings ("vogue" and "uproar") into English, only to have furor appropriate them into an expanded set of meanings, or did furor contain both of those meanings all along? Let's look at some older dictionary definitions.


Older dictionary treatments of 'furor' and 'furore'

The earliest general dictionary entry I can find for either word is from Edward Phillips & John Kersey, The New World of Words: Or, Universal English Dictionary, sixth edition (1706), which offers entries for furor and for the medical term furor uterinus:

Furor, (Lat.) Fury, Madness, Rage.

Furor Uterinus, (i. e. Womb-fury) a strange Distemper, which provokes Women to transgress the Rules of common Modesty, without restraint.

However, a slightly earlier medical dictionary also mentions furor and expatiates on the "strange Distemper" of furor uterinus. From Stephen Blancard, The Physical Dictionary: Wherein the Terms of Anatomy, the Names and Causes of Diseases, Chyrurgical Instruments, and Their Use, Are Accurately Describ'd, second edition (1693):

Furor, the same with Manea [defined under Mania as "a sort of Madness, a deprivation of Imagination or Judgment, with great Rage and Anger, but without a Fever and Fear. It proceeds from Sulphureo-Saline Animal Spirits, like Aqua stygia, which cause strange furious impulses in the Body, not by consent of Parts; but by their own Strength."].

Furor Uterinus, an unseemly Distemper, which is wont to seize upon Maids ; especially those of riper years, and sometimes Widows too. They who are troubled with it, throw off the Veil of common Modesty and Decency, and delight only in Lascivious, Obscene Discourses : They covet a Man greedily, and even furiously, and omit no inviting Temptations that may induce them to satisfie their desires. The cause seems to be in the Seminal Juice, which being exalted to the highest degrees of Maturity, drives the Maids into a kind of Fury ; which is conspicuous every Year in some Bruits ; as in Cats, Bulls, Bucks, Does, Harts. ...

The source of this analysis, according to Ephraim Chambers, Cyclopaedia: Or an Universal Dictionary of Arts and Sciences (1741) was Daniel Sennert, a German physician whose Nine Books of Physick and Chirurgy was translated into English in 1658. Nathan Bailey, Universal Etymological Dictionary, second edition (1724) has an entry for furor uterinus, but not for furor alone:

FUROR Uterinus, a Distemper which provokes Women to transgress the Rules of common Modesty. L.

Bailey's Dictionarium Britannicum: Or a More Compleat Universal Etymological English Dictionary (1730) does have entries for both terms:

FUROR, fury, madness, rage, L.

FUROR uterinus {with Physicians} i. e. the fury of the womb, a species of madness peculiar to women, exciting them to a vehement desire of venery, and rendering them insatiate therewith, L.

But the definition for furor uterinus that appears in his 1724 Universal Etymological Dictionary appears instead as the definition of nymphomania.

Most eighteenth- and nineteenth-century British English dictionaries have no entry for furor at all. Perhaps most surprisingly, furor doesn't appear in editions of Samuel Johnson, A Dictionary of the English Language, from the first edition (1755) to the ninth edition (1806), nor in H.J. Todd's two revisions of Johnson's Dictionary—the first edition (1818) and the second edition (1827), indicating that the word wasn't widely used in England from the middle decades of the eighteenth century until well into the nineteenth century. As late as 1881 an edition of John Walker's A Critical Pronouncing Dictionary, updated by Edward Smith, has nothing on furor or furore.

In the United States, Joseph Worcester, A Comprehensive Pronouncing and Explanatory Dictionary of the English Language (1830) has no entry for furor. The word does appear in Worcester's A Universal and Critical Dictionary of the English Language (1846), but Worcester puts it in italics:

FUROR, n. {l.} Fury; madness; rage. Sir T. Wyatt.

In a usage note at the front of this dictionary, Worcester remarks, "Words printed in Italics, in the Vocabulary are words which belong to foreign languages, and are not properly Anglicized."

The earliest Webster’s dictionary to include an entry for furor seems to be An American Dictionary of the English Language (1847):

FUROR, n. {L.} Fury ; rage.

The 1864 edition of An American Dictionary of the English Language only slightly alters the entry:

FUROR, n. {Lat. from furere, to rage. Cf. FURY} Fury ; rage.

The breakthrough occurs with Webster's International Dictionary (1890), which has these entries:

Furor, n. {L. Cf. FURY} Fury ; rage.

Furore, n. {It.} Excitement; commotion; enthusiasm.

I can't replicate the pronunciation symbols that this dictionary uses, but it specifies that furor is a two-syllable word pronounced "fu´-ror," while furore is a three-syllable word pronounced "foo-ro´-ra."

A scant 19 years later, however, Webster's New International Dictionary (1909) reported the merging of the two words and their meanings in the single spelling furor:

furor, n. {L. : cf. F. fureur, OF. also furor. Cf. FURY.} 1. Fury ; rage ; also, madness or mania ; sometimes, specif., the "frenzy" or "enthusiasm" of poets or inspired persons. 2. A public or contagious enthusiasm or excitement ; esp., a prevalent and excited admiration ; a "rage" ; a "craze."

That was quick. As of 1909, we have all but one of the meanings that appear in the Eleventh Collegiate Dictionary (noted at the start of this answer). The exception is the "furious or hectic activity/outburst of indignation: uproar" meanings that appear as definitions 4a and 4b there.


Changing entries for 'furor' and 'furore' during the past 100 years

An entry for furore reappears in Webster's Fifth Collegiate (1936), along with an entry for furor:

furor n. 1. Fury; frenzy. 2. Poetic or religious enthusiasm. 3. A prevalent and excited admiration; a "rage" a craze.

furore n. Furor; a "rage."

According to this dictionary the pronunciation of furor is "fū´-rôr" and the primary pronunciation of furore is "fū´-rōr"—although it also lists a three-syllable pronunciation of furore that is similar to the one that appeared in the 1890 Webster's International.

The next change comes with the Seventh Collegiate (1963):

furor n 1 a : ANGER, RAGE b archaic : a state of fervent inspiration : FRENZY 2 : FURORE

furore n 1 : a contagious excitement; specif : a fashionable craze 2 : a public disturbance

This dictionary gives a pair of two-syllable pronunciations for both words, in reverse order: "'fyu̇(ə)r-ȯ(ə)r" and "'fyu̇(ə)r-ō(ə)r" for furor, and "'fyu̇(ə)r-ō(ə)r" and "'fyu̇(ə)r-ȯ(ə)r" for furore. The three-syllable pronunciation of furore is gone—but it returns as a third pronunciation ("esp Brit") in the Eighth Collegiate (1973) a thoroughly revamped set of definitions for the two words that has remained unchanged through the most recent (2003) Eleventh Collegiate.

The "outburst of indignation" sense of furor and furore has been lurking at the periphery of the "commotion" meaning of furor/furore since 1890, but Merriam-Webster didn't identify it as a distinct sense of the word until 1963.


Contextual note: 'furor' as madness during the period 1700–1900

As I suggested in the first part of my answer, furor had a specifically medical/psychological meaning for more than 200 years, and that meaning seems to have been considerably more common than any competing meaning in English texts. Very early instances of the word use it in the sense of anger or rage, as is the case with Henry Howard, "Complaint of the Absence of His Love" (by 1547), in Poems of Henry Howard, Earl of Surrey, Who Flourish'd in the Reign of Henry the Eighth (1717):

And yet with more delight to moue my wofull case,/ I must complaine these hands, those armes, that firmly do Embrace./ Me from my selfe, and rule the sterne of my poor lyfe,/ The sweet disdaynes, the pleasant wrathes, and eke the louely strife./ That wonted well to tune in temper just and mete,/ The rage, that oft did make me Err by furour vndiscrete.

But a Google Book search results from about 1700 forward shows a preponderance of instances of furor in the sense of mania or passion.

From Jonathon Swift, “A Discourse Concerning the Mechanical Operation of the Spirit” (1704):

I think, it is agreed among physicians, that nothing affects the head so much, as a tentiginous humour, repelled and elated to the upper region, found by daily practice to run frequently into madness. A very eminent member of the faculty assured me, that, when the quakers first appeared, he seldom was without some female patients among them for the furor—persons of a visionary devotion, either men or women, are in their complexion of all others the most amorous: for zeal is frequently kindled from the same spark with other fires, and, from inflaming brotherly love, will proceed to raise that of a gallant.

From Thomas Brown, Letters from the Dead to the Living, Part 2 (1707)

A Noble Peeress, that lives not full a Hundred Miles from St. James's-Square, in the Sixty fifth Year of her Age, was seiz'd with a Furior Uterinus ; By plying her Ladyship with a few Drops of my Antepyretical Essence, extracted from a certain Vegetable gather'd under the Arctic Pole, and known to no body but my self, I perfectly allay'd this preternatural Ferment ; and now she lies quiet, tho’ both her Hands are untied, as a new swaddled Babe, and handles no Raskals but Pam, and his Gay Fellows of the Cards.

From a review of Kristni-Saga, in The Monthly Review, or, Literary Journal (January 1776):

The first gives an account of the Berseki: a kind of bruisers, in ancient times, who were seized, by intervals, with the wildest furor; during which they plunged themselves into the greatest dangers, and committed the most horrid outrages. They are frequently mentioned in the monuments of Northern antiquity. These fits of madness, which seized them on a sudden, were soon over; but during such a paroxysm, their strength is said to have been more than human; and that not even fire, if we can believe it, nor any weapon, could hurt them.

From a review of Drury’s Illustrations of Natural History, in The Monthly Review (July 1783):

The Norway rats are so numerous and so bold, that they will come and feed by the side of the table at supper, and during the still hours of the night, search every corner for plunder, making a continual uproar, and often, in a kind of furor, carry away small utensils, and other articles, which they can turn to no advantage either for food or shelter. They are very mischievous to the naturalist's collection of plants and feeds, tearing them, and the books in which they are kept, in pieces, as it were in wantonness, and carrying away such as are edible, in which they are assisted by the land-crabs.

This last instance is notable as being one of the earliest one (aside from Henry Howard's, from the first half of the sixteenth century) that my Google Books searches turned up in which furor is not italicized as a foreign word. Besides these instances, there are numerous references between 1686 and 1908, especially in the latter half of the nineteenth century, to furor uterinus in a strictly medical sense, as well as other diagnosed furors.


'Furore'—and similar senses of 'furor'—in the wild

My 1971 edition of the Oxford English Dictionary cites Thomas Carlyle in 1851 as providing its first occurrence of furore:

furore Enthusiastic popular admiration ; a ‘rage’, ‘craze’. [Cited examples:] CARLYLE in Froude Life (1884) II. 83 This blockhead .. is ..making quite a furore at Glasgow. 1864 LEWINS H. M. Mails 263 It was little thought that .. they would excite such a furore among stamp collectors. 1867 DICKENS Lett. 25 Nov., If we make a furore there.

Carlyle's remark occurred in the context of a letter (dated September 10, 1851) in which he discusses an Italian lecturer in the neighborhood of Scotsbrig, Dumphries (where Carlyle was then staying):

Father Gavazzi is going to harangue them [at Dumphries] to-morrow in Italian, which one would think must be an extremely unprofitable operation for all but the Padre himself. This blockhead, nevertheless, is actually making quite a furore at Glasgow and all over the west country, such is the anti-Popish humour of the people.

The William Lewins quotation is originally from "The Stamp Mania," in Chambers’s Journal (June 6, 1863):

When postage-stamps were first introduced in England, it was little thought that they would become a medium of exchange, and far less that they would excite such a furore among stamp-collectors.

Here there is no circumstantial Italian angle to justify the choice of furore; still, the word appears in italics to signify its foreignness. The word goes unitalicized in the Dickens instance, which is from a letter he wrote in Boston on November 25, 1867, reprinted in The Letters of Charles Dickens, volume 2 (1880):

Communications about readings incessantly come in from all parts of the country. We take no offer whatever, lying by with our plans until after the first series in New York, and designing, if we make a furore there, to travel as little as possible.

It seems most probable that furore crept gradually into the consciousness of English speakers over several decades during which it sporadically appeared in the conversation or writings of persons who spoke Italian. Because two of the OED's earliest three cited instances involve private letters, the term seems unlikely to have burst into public use from those sources.

The use of furore to mean "commotion or uproar" seems to have occurred at very nearly the same time that furor acquired the same meaning. It bears repeating that furor was widely treated as a foreign word in English well into the nineteenth century and that—for much of its several centuries of prior presence in English—it was primarily a medical term with a similar meaning to mania, used especially in the term furor uterinus, which eventually gave way to the term nymphomania. An item titled “Santluss on the Conditions of Insanity in Men, and Their Bearing on Responsibility” in The London Medical Record (July 31, 1875) offers this graphic description of how furor and mania differ:

The distinction between mania and furor is shown by a story by Reil. A woman, during her pregnancy, has an incessant craving to eat the flesh of her husband. She kills him, and pickles him. The killing was the furor, the craving was the mania.

Furor in the sense of "negative uproar" occurs in "Where is the Man with the Ether?" in Journal of Zoöphily (June 10, 1910):

Another step was taken by the defenders of vivisection to divert the growing movement for regulation of the practice is the removal from public sale of all copies of the volume on "Surgical Shock," written by Dr. George W. Crile. This book, when it made its appearance in 1899, caused a furor of indignation, not only on the part of the general public, but also among medical men.

An article titled "High Finance in the Milk Trade," in The Pacific Dairy Review (January 6, 1910) contains an instance of furore as "negative uproar":

Back in New York city the advance in the price of milk to nine cents a quart has caused a great furore among the consumers, which finally resulted in an official investigation as to the existence of a "trust" that is able to fix prices.

Those consumers were clearly not expressing admiration at the price increase. Thirty years earlier, this instance arose in "Testimony of J. W. Cromwell" on January 19, 1880, in Proceedings of the Select Committee of the United States Senate to Investigate the Cause of the Removal of the Negroes from the Southern States to the Northern States (1880):

Q. What do you know, anyway, about this exodus?

A. ... I was surprised to find such a unanimity of feeling on the part of the conference in favor of emigration from the Southwest. There was a positive furore about it; so much so that some of the other business for which the conference was called could not be attended to.

...

You say there was a furore in that convention, or conference, on the subject of emigration; what was the origin or cause of that furore?

A. Well, it had its origin in the complaints of the colored people.

Here furore may be intended in the sense of "enthusiasm" or "popular excitement," but it can easily be read as well as involving "positive commotion" and "positive uproar"—and those notions are less distant from "negative commotion" and "negative uproar" than one might think.

At the same time, furor has sometimes appeared in the "popular admiration" sense, as it does in William Ostler, “Tuberculosis,” in A System of Practical Medicine, volume 1 (1897):

Tuberculin.—The announcement by Koch that he had obtained a material which exercised a specific curative action on a tubercle caused a furor of excitement never, perhaps, equalled in the history of medicine. At present we are deep in the reaction following the failure to substantiate that claim.

Again, this instance of furor seems to have much the same meaning as the instances of furore in the preceding example.


Conclusions

Here are my provisional answers to the three posted questions.

1. What (a book, a play etc.) made "furore" a term adopted by the English language in the late 18th century with a different connotation from its original one?

There was no breakthrough instance of usage that propelled furore into English—certainly not in 1790. It seems clear to me that furore introduced the "positive excitement or enthusiasm" and "fashionable craze" senses that furor later to some extent took over. But furor was itself an out-of-the-mainstream word during the 1700s and 1800s, so it isn't surprising that English speakers weren't clear about where the meanings of furor stopped and the meanings of furore began.

That furore rather quickly lost its original sense—or at least became fuzzy—is evident from this discussion in "The Italian Element in English" (1929):

Furore was coined by the same nation which first used the word voga (i.e., vogue) for 'a fashion': to make a furore translates the Italian far furore. The present use of the word in England seems to have slightly altered from its source. For instance in Aloysius Horn (The Ivory Coast in the Early Nineties, 1927, p. 38: "Writing’s always been a bit of a furore with me").

The alteration in this instance seems to involve the personalization of what is ostensibly a group phenomenon. But confusion between furor and furore had even more problematic aspects.

2. When, roughly, did its meaning "enthusiastic popular admiration" start to die out?

Although none of the dictionaries that I consulted agree that furore in the sense of "enthusiastic popular admiration" is obsolete, a Google Books search doesn't turn up any matches for furore in that sense from recent years. I suspect that widespread use of furore to mean "vogue, rage, craze, or fad" was actually rather short-lived, for several reasons.

First, Merriam-Webster's 1790 origin date notwithstanding, furore seems not to have achieved even limited popular usage until the 1820s (as detailed in my other answer to this question), and the "vogue" meaning was not well established before the competing "positive or negative public excitement or uproar" meaning began to catch on in the 1840s, confusing the issue of which meaning was intended. The earliest dictionary I've found that includes an entry for furore is Webster's International Dictionary from 1890. Second, the status and meanings of furor weren't well settled in popular English either, adding to the confusion surrounding furore. Third, multiple unambiguous alternatives for the "vogue" sense of the word were available—and English speakers and writers evidently took them.

3. Is "furore" currently used as a close synonym of "furor," or does it carry different nuances in BrE and AmE?

The dictionaries I cite earlier in this answer indicate that furore has two meanings, and that those meanings are identical to two of the five meanings that furor has. I'm not aware of any U.S. English speakers who treat furor and furore as having distinctly different meanings—although there must be some. In any event, most U.S. English speakers use furor to the exclusion of furore.

I can't speak to British English tendencies, other than to note that furore appears to be significantly more common in British English sources than in U.S. English sources. But whether some, many, or most British English speakers and writers consistently use furor and furore to signify different things, I do not know.


My previous answer focuses on dictionary entries for furor and furore and instances of the words that Google Books searches return. Here I will focus on relevant newspaper instances of the terms.


Early matches for ‘furore’ in British newspapers

A British Newspaper Archive search finds furore in use by 1819. Here are the first six matches from that database (which I do not have a subscription to, and so cannot confirm OCR corrections, resolve ambiguities, or note the presence or absence of italics).

From an item in the Bristol [England] Mirror (December 1, 1819):

... LISDLKY, who, far from conceiving himself disgraced playing in it, we are credibly informed selected the trio himself [as] one the pieces for the evening. So much for the veracity of X. Y. The furore which this piece excited, was not confined few individuals, but was general throughout the whole assembly.

From “Theatres,” in the [London] Morning Post (October 15, 1824):

The performance of the Overture was listened to with intense silence, and its close was followed by a degree of enthusiastic applause, which raised the idea of an Italian audience tutto[?] furore. In fact, it was one of the finest instrumental achievements we ever heard in our national Theatres.

From “Newspaper Chat” in the [London] Examiner (April 3, 1825):

At Florence, we learn from the same journal, the Opera was received with great furore; during the first three evenings, the Composer was regularly summoned to make his appearance at least four times during the course of the piece in order to receive the congratulations of a very full house. The singers were also called to share the same tribute of applause ...

From “Sporting” in the Edinburgh [Scotland] Evening Courant (January 5, 1828):

The exertions in this grand scene must have been prodigious; but for this, it would have been encored, for the applause which ensued at its conclusion was long and loud, indeed it was quite a furore. Signor De Begnis’s imitation of female voice was capital. In the scene where he is giving his servant a few specimens of the latest...

(This same story is repeated two days later in the London Evening Standard under the title “Italian Opera in Edinburgh.”)

From “The Theatre” in the Norwich [England] Mercury (June 7, 1828):

Upon the first introduction of the opera of Der Freischutz among the romantic natives of Germany, nothing could exceed the furore with which it was received and followed in all the continental cities where it was performed.

From “Fashion and Table Talk,” in the [London] Globe (April 14, 1830):

... appearance, is considered as Bellini’s chef d'oeuvre, although many persons at Milan prefer his Straniera, in which Madame Meric Lalande caused a furore in Italy. The next best opera for that lady is Pacini’s Ultimo Giorno di Pompei, which will be delayed till the arrival of Blanche, who ...

Evidently, furore emerged in British newspaper usage in the context of musical performances—in particular, opera.


Early matches for ‘furore’ in Australian newspapers

An Elephind search finds six unique instances of furore from the 1840s in Australian newspapers evidently reprinting items from English papers. From “Latest Parisian Fashions” in the Launceston [Tasmania] Advertiser (October 20, 1842), quoting the [London] Post:

As to the manteau cardinal, it is a perfect furore— the warehouse of Delille, in Paris, is the general rendezvous of the elegantes of Paris, and hardly can they suffice for the orders they receive. This costume is likely to hold for a length of time its vogue, for its expense renders it exclusive.

From “A New Composer,” in the [Adelaide] South Australian (August 22, 1845), quoting from the [London] Morning Chronicle, we have this:

When the performance began, the commencement of a piece by an author whom nobody knew, was listened to with indifference. Attention, however, was gradually roused, and rose to the utmost enthusiasm. Since that time "Le Desertabas been performed repeatedly to crowded audiences, and the furore in its favor continues to go on increasing.

From “France” in the [Adelaide] South Australia Register (May 15, 1847):

A new dance, called ' La Napolitaine,' is creating a perfect furore in the salons of Paris, and seems likely to usurp that dominion which the Polka held during the former two seasons. It is the composition of Madame Michau, of Brighton, sister of Mr D’Egville, late of Worcester.

From “Gun Cotton,” in the [Launceston, Tasmania] Cornwall Chronicle (June 16, 1847), reprinted from the Adelaide Observer:

The egg of Columbus now stands erect—everybody makes fulminating cotton; ’tis very easy when one knows the way; and various are the opinion as to the ultimate extent of its application to fire-arms of different kinds. In obedience to the present explosive furore, we, too, have made experiments in connection with this subject, and will proceed to indicate to our readers some of the results to which we have arrived.

From “English Extracts: Revolution and Opera,” in the Sydney [New South Wales] Australian (September 14, 1848):

The musical world is turned -upside down. The furore just now is to hear, or rather see, Rachel sing, or, rather ‘act,’ the Marseillaise; which is said to be a very remarkable performance, but by no moans in the Italian style.

And from “National Emigration,” (April 28, 1849), in the [Hobart, Tasmania] Courier, reprinted from the [London] Times (January 3, 1849):

For our own part, we cannot think the case to be exactly the same now as it was in January, 1847, or even in January, 1848. Since the former date half a million of souls have left these [British] shores; and since the latter date this unexampled emigration has assumed the form of a spontaneous and regular stream. Nor is there any visible abatement of the locomotive furore. We may therefore conclude that, fur some time to come, nearly the whole annual increase of our home population will take wing.

In this last example, the “admiration” component of “enthusiastic admiration” has vanished, and we are left with simple (but powerful) “enthusiasm.”


Early matches for ‘furore’ in U.S. newspapers

The earliest U.S. instance of furore that Elephind searches identify is from “Ole Bull,” in the New York Daily Tribune (November 25, 1842):

At the Neapolitan theatre of San Carlos, he [Bull] was summoned back by the public no less than nine times—thrice after the performance of his first piece, and six times at the end of the second. It was a perfect furore. Our Norwegian artist now revisited Paris, under happier auspices.

From an untitled item in the [Indianapolis] Indiana State Sentinel (December 31, 1846), reprinted from the New York Globe:

The forty children from Europe, who pass under the cognomen of Les Danseuses Viennoises, are attracting a good deal of attention in New York city. The Globe says:

Their performances are certainly the most wonderful and pleasing ever submitted to the public, and met with the most decided success. Their dances consist of groupings in figures of classical beauty—now resembling baskets of luscious fruit—now like clusters of flowers, harmonious in color and graceful in form, and then, by the easiest and most uniform movements, forming beautiful spiral shells, or that chariot of the water nymph, the elegant nautillus. Their wonderful and novel performances created quite a furore.

And from “California Fever Abating” in the Galveston [Texas] Weekly News (March 23, 1849):

Nevertheless, a goodly number of tall youth have departed. But more of the ''real stuff" will have to be seen—"seeing is believing" before a new furore commences and more Jasons set sail after the golden fleece.

It’s noteworthy that this instance of furore uses the term not in the sense of “enthusiastic admiration” but in the sense of something closer to “mass mania.”

Another early instance appears in “Jenny-Mania,” in the Richmond [Virginia] Enquirer (September 10, 1851):

To-morrow night the divine Lind gives her first concert in the monster-room at Castle Garden, which will hold about 8,000 persons. The furore of the New Yorkers may be judged by the fact that, at the auction of the tickets on Saturday, the first choice of seats was knocked off at the enormous price of $225 to Mr. Genin, a Broadway hatter, who was cheered by the audience.

But both furore and furor appear in very similar senses, just a month apart in 1851, in competing Pittsburgh newspapers. First from “From New York,” in the Pittsburgh [Pennsylvania] Gazette (June 4, 1851):

Yet she was received with considerable enthusiasm, and the immense audience appeared perfectly satisfied with her performance. The more I see and hear Jenny Lind, the more difficult it is for me to appreciate the justice of the furore which she has excited in the fashionable and musical world[.]

And second from “Dan Rice’s Circus,” in the Pittsburgh [Pennsylvania] Daily Morning Post (July 3, 1851):

Dan opened last night on Penn Street, opposite the American hotel, and his spacious pavilion was filled to overflowing by one of the most enthusiastic audiences we ever saw. High expectations had been raised by the furor which the company had created along the river, but we feel safe in saying that they were fully realized.

There is little difference in meaning between furor in this example and furore in the previous one.


Conclusions

The newspaper evidence suggests that furore in the sense of “popular excitement and admiration” originated in British English and had gained some currency there, particularly in theatre circles, by the 1820s. The connection between furore and Italian opera during the 1820s is striking. By the 1840s, furore had spread from England to Australia and the United States. But confusion between furore and furor seems to have been present in U.S. English from a very early point in the former term’s existence in the United States.