Why is 'forty' spelled without a 'u' in Canadian/British English?

I was writing in Word today (with the Canadian English dictionary enabled) and it kept putting a redline under "fourty" which I couldn't understand. A bit of searching says that, even in British and Canadian English, the spelling is indeed "forty" but without any real explanation.

http://en.wikipedia.org/wiki/40_%28number%29
http://crofsblogs.typepad.com/english/2006/06/forty_or_fourty.html

It seems slightly counter-intuitive as we learn to spell so many words with the extra 'u' in Canada, and of course, some Canadian websites will actually write "fourty".

http://www.hnb.ca/en/home/474-fourty-four-of-atlantic-canadas-best-invited-to-team-atlantic-summer-evaluation-camp

So why do we have four and fourteen, but not fourty?

Update: So I guess really the answer is that, unlike a lot of other words that may or may not be spelled with a 'u' in "recent" times (i.e. when American English became a standard), this has been spelt as "forty" for ages.

Solution 1:

Before 1600, the OED gives citations where forty is spelled in various ways, but never with just an "o" vowel:

feuortig, feortiȝ, fuwerti, uourty (the "u" is really a "v"), fourty, fourthi, fourtie

This might possibly mean that there was some actual diphthong leading to these spellings; since most of these spellings occurred before there was any standardization, it is hard to tell either way.

In 1600, there are three citations, and, interestingly, all of them have just "o":

1602 Contention Liberalitie & Prodigalitie i. iv. sig. B2, "Cham sure chaue come, vorty miles and twenty."

a1642 J. Suckling Poems (1646) 37, "And there did I see comming down Such folks as are not in our Town Vorty at least, in Pairs."

1698 J. Fryer New Acct. E.-India & Persia 94, At the end of their Quarentine, which is Forty days.

(We can ignore the "v/f" alternation — something was apparently going with the voicing at the beginning of this word, but it probably has no bearing on the vowel following it.)

Aside from one citation in the 1700s that uses fourty, everything else from then on is written as forty.

One can only guess the reason for this change (at least with the information that I have) — whether it was pronunciation shifting or just orthographic simplification. But I might have an explanation for why this spelling took hold so swiftly in the 1600s: the Bible. The King James edition of the Bible was a major influence on the standards in English spelling. The KJV Bible was published in 1611 (begun in 1604), and (since I happen to have a KJV corpus handy) I see that there are 158 tokens with the spelling forty in KJV and 0 tokens for fourty.

So, even if the spelling of forty was following the whim of a handful of publishers, it got into the King James Bible, and that was that.

Solution 2:

The other answers here have a good summary of the history of the spelling of this word, but:

To be clear, in contemporary English, the standard spelling is forty in all standard dialects and varieties. The spelling fourty, though it has historical precedent, does not have any currency. It is not listed as a modern spelling in any dictionaries.

Solution 3:

Here:

In Old English, it was spelt feuortig...by the 14th century (Chaucer) it was spelt fourty... and not until the very end of the 17th century was it spelt forty. In other words, it - like multitudes of other English words - went through a process of simplification over time.

Solution 4:

The words four and forty obviously have the same root if you go back far enough, but they were actually pronounced with distinct vowel sounds in many past dialects of English (and still are in some present ones). Four was pronounced with a "long o" sound, while forty was pronounced with a "short o" sound.* Apparently, the vowel in forty was shortened at some point in history (the spelling variations may give some clue; another way to find out would be to see what pronunciations were recommended by orthoëpists at different times). This is analogous to the difference in the pronunciation of the "ow" in know and knowledge.

How does this relate to the spelling? Well, in general, the digraph "ow/ou" is not used in English to represent a "short o" sound. The word knowledge that I just mentioned is an exception, but there are not many other words like it. So for speakers who pronounce forty with a "short o" sound, the spelling forty reflects the pronunciation better than the spelling fourty. I would guess this contributed towards the eventual standardized spelling without "u".

More details about these two vowel sounds

In John Wells's system of lexical sets, the vowel sound in four (historically a "long o" followed by "r") is called the "FORCE" vowel, while the vowel sound in forty (historically a "short o" followed by "r") is called the NORTH vowel.

If you pronounce these words with the same vowel sound, it means you have the horse-hoarse merger. This merger is part of the "standard" dialects in England and North America, so most general-purpose dictionaries transcribe these words with the same vowel.

In varieties of English without the merger, the exact way these vowel sounds are distinguished varies among different accents. In old-fashioned British "Received Pronunciation," words with the FORCE vowel were pronounced with a centering diphthong transcribed /ɔə/, while words with the NORTH vowel were pronounced with the monophthong /ɔː/ (identical to the vowel found in words like THOUGHT). Wells says /ɔə/ merged into /ɔː/ for most British speakers during the early twentieth century.

Rhotic (r-pronouncing) varieties of English that distinguish these two vowels usually have a phonetically higher vowel in FORCE words (something like /or/ or /oʊr/, which could be characterized as the GOAT vowel followed by the consonant /r/) and a phonetically lower vowel in NORTH words (/ɔr/ or /ɒɹ/, which could be characterized as the THOUGHT or LOT vowel followed by /r/). Here are some audio samples I found on Youtube of a western Scottish, young female speaker's NORTH and FORCE vowels.

*Here are some relevant links that mention this fact:

entry for forty in Walker's Critical Pronouncing Dictionary of 1791
“Interstate Farty-Far” (St. Louis English)
Linguistlist message: Provenance of /Or/ > [ar] / __@ ?
"Kansas City and Its Vowels," by Christopher Strelluf (see page 79)
this post at John Wells's phonetic blog (see the comments)