/ð/ → /d/ shift in English

1. When did this consonant shift happen in English? Etymonline mentions 12c.

Everybody has their own set of pronunciation habits. /ð/ can be pronounced in various ways and still be distinguishable because its existence is easily predicted/"auto-interpreted" by the brain. /d/ or /dð/ are common variants. It would be very hard to say exactly when such a shift occurred in the English language given that these transitions happen over time, unless an obvious answer exists like "The High Shift", but that's pretty unique, that's why it has its own name :P

2. What are some more examples of the /ð/ → /d/ in English words?

I'm not sure what "in English words" specifies in your question. I assume you're asking for words where the English /d/ takes place of the German /th/, i.e., words that are the 'opposite way', since words that illustrate the 'High Shift' are easy to think of/find.

Assuming you were asking for examples of /ð/ → /d/ -- so words where the English /d/ replaces the German /th/:

• dollar / thaler (see note below)
  

For the rest of the list that follows, ignore the spelling of the German words, think of the pronunciation instead. Of course this will vary from person to person, but these are arguably at least semi-aspirated /th/ sounds as opposed to just a 't' sound. Invariably though, this all depends on how hard you enunciate the latter half of the sound. I'm not going to pedantically look up the pronunciation guides in a dictionary, I have several relatives who speak German. Some aspirate the /h/ part of /th/ quite heavily, and others barely at all. You decide whether they count or not.

• devil / teuful
• day / tag
• door / tür
• deaf / taub

The Dollar / thaler pair is a good specific example of cognates with this particular shift. A Thaler is an old unit of currency from which "dollar" also gets its name. I mention this specifically in response to your question:

This means a shift from /ð/ → /d/ also happened, doesn't it?

I can't cite a particular 'shift' occurring in that direction, but the shift is definitely not one-way, perhaps they are simply commutatively understood and thus interchangable? If one were looking for evidence or trying to convince his peers of a 'reverse shift' having occurred, this is a pretty good lead-in that supports that theory.

You obviously know about the opposite way (high Germanic shift, English /th/ replaces the German /d/) but since I wasn't positive which shift you were asking for more examples of, I'll include some of this kind too:

• thank / danken
• leather / leder
• three / drei
• earth / erde
• bath / bad
• forward / vorwärts
• word / wort

[Again, for some of these...it's pronunciation, not spelling of course :)]

3. How is the shift mirrored in other Germanic languages?

Firstly the easiest thing to explain: Olde English ignored the shift completely. No effect there.

The fourth phase of the High German Shift, þ/ð→d occurred around the 9th/10th century, based on historical Old High German-Language books containing the old/unshifted version from around that time period. There was a lot more to the High German Shift than this particular mutation... although it was the most impactful & important. The first three phases of the High German Shift affected voiceless plosives, leading therefore to mostly isolated changes (High German only. Lower German was mostly unaffected.)

The fourth phase shifted the dental fricatives to /d/. This is distinctive in that it also affects Low German and Dutch. In early Old High German, as in Old Dutch and Old Saxon, the voiceless and voiced dental fricatives þ and ð stood in allophonic relationship (as did f/v and s/z), with þ in final position and ð used initially and medially. The sound ð then became /d/, while þ became /t/. This shift occurred late enough that unshifted forms are to be found in the earliest Old High German texts, and thus it can be dated to the 9th or 10th century. It took several centuries to spread north, appearing in Dutch only during the 12th century, and in Frisian not for another century or two after that.

Things to read:

• http://en.Wikipedia.org/wiki/High_German_consonant_shift#.C3.BE.2F.C3.B0.E2.86.92d_.28Phase_4.29
• http://en.Wikipedia.org/wiki/Old_High_German
• http://en.Wikipedia.org/wiki/Grimm%27s_law
• http://en.Wikipedia.org/wiki/Armenian_language#Evolution
• http://en.Wikipedia.org/wiki/Glottalic_theory
• The Uralic Hungarian language was also affected by a similar process, leading to a high frequency of f and h, and can be compared to Finnish, which did not change this way.
• http://web.cn.edu/kwheeler/IE_Main5_Grimm.html

Hope that helps.

The voiced dental fricative [ð] and the voiced coronal plosive [d] are similar sounds, but they did contrast in Old English. However, [ð] did not contrast with the equivalent voiceless fricative [θ], so [ð] in Old English is not considered a phoneme, but an allophone of a dental fricative phoneme that was unspecified for voicing, which we could transcribe as/þ/ (since the letter thorn, "þ", was used in Old English to write either [θ] or [ð]).

An example: the word fæder "father" had the phoneme /d/, but the word broþor "brother" had the phoneme /þ/ (realized as [ð]).

Here are some quotes describing the development of these sounds from Dental fricatives and stops in Germanic: deriving diachronic processes from synchronic variation, by Bridget Smith 2007:

Old English, as the other West Germanic languages, showed evidence of strengthening of Verner’s /ð/ to /d/ (for a more detailed discussion of Verner’s Law, see section 3). This is why there was only one dental fricative phoneme, /θ/, and a voiced allophone, /ð/. However, there was variation between /ð/ and /d/ in medial positions, often attributed to analogy -- paradigmatic, semantic, fourpart, and other; for example, burden vs. burthen, fader vs. father, murder vs. murther. It is also possible that early Scandinavian influence, with its medial fricatives, compounded this situation, which persisted well into Middle English, though it should be noted that Old Saxon also demonstrates this type of variation in medial positions.

In Section 3:

There are differences in how the individual Germanic languages handled the dental fricative [Proto-Germanic *ð] after the reconstructed proto-language stage, with some of them making multiple changes in place, manner, and/or voicing. The main thrust of changes seems to favor neutralization of the voicing distinction, or a change of one or both phonemes in manner of articulation to stop or approximant. In West Germanic, all instances of /ð/ hardened into stops, leaving only the voiceless dental fricative. In Old High German, Grimm’s /θ/ eventually became /d/ and /ð/ became /t/ (essentially reversing Verner’s and Grimm’s Laws in this respect). By the 8th century, /ð/ had changed to /t/, presumably having first become /d/, as in Old English, then becoming /t/ during the High German Consonant Shift. [...]

Old English regained voiced /ð/ from voicing assimilation of /θ/, (baþian > [baðian]) and some instances of /d/ became /ð/ in Middle English, either by analogy or medial weakening (burthen, mother), and a few instances of /ð/ became /d/ (murder).

The paper also discusses development in other Germanic languages; I'd recommend reading the whole thing.

One thing I've read in multiple sources is that variation between /ð/ and /d/ in English was particularly common in words ending with a vowel or the liquid r plus -der/-ðer. (But this variation doesn't seem to have had any currently visible effects on words that end in a suffix -er, such as the noun leader or the inflected adjective redder.)

For example, the Oxford English Dictionary's entry for father says:

The spelling in our quots. is uniformly with d until 16th cent., except that faþer occurs sporadically in the Cotton and Göttingen MSS. of the Cursor Mundi (a1300); but the pronunciation /ð/ may have been widely current in the 15th cent. or even earlier; in 14–15th cent. the spelling with -der is very common in words like brother, feather, leather, though this spelling cannot in all cases be supposed to indicate that the writers pronounced the words with /d/ . The modern English -ther /ðə(r)/ for Old English -der, -dor in father and mother is often wrongly said to be due to the analogy of brother, or to Scandinavian influence; it is really the result of a phonetic law common to the great majority of English dialects; other examples in standard English are gather, hither, together, weather. At present nearly all dialects pronounce father and mother with /ð/ as in standard English; in various parts of the north of England and the north Lowlands /d/, alveolar or dental, is sometimes heard.

The interesting thing about brother, feather and leather is that they actually did not have /d/ in Old English (they come from OE broþor, feþer, leþer) so the use of "d" in some historical spellings of these words cannot indicate an unshifted inherited /d/; either it is a way of spelling /ð/ or it is the result of a sound change from OE [ð] (phonemically /þ/) to /d/ (but if this sound change happened, it was either reversed or did not occur in these words in the ancestor of modern standard English).

Here are relevant word pairs that I have found in Old and Modern English showing interchange of d and th (or [d] and [ð]):

d > th:

• OE mōdor > mother
• OE fæder > father
• OE gad(e)rian > gather
• OE tōgædere > together
• OE weder > weather
• OE hider, hwider, þæder/þider > hither, whither, thither

The reverse change also occured:

þ > d:

• OE spīþra > spider
• OE rōþor > rudder
• OE morþer/morþor/morþur/morþre > murder (this word may have been influenced by French forms)
• OE byrþen/berþen > burden (unusually, this one does not end in -er)

And Modern English does have a number of words ending in a vowel plus -der that had /d/ in Old English:

d > d:

• OE hlǣd(d)er > ladder
• OE blǣdre > bladder
• OE nædre/næddre > adder
• OE mædre/mæddre/mædere > madder (the plant)
• OE fōdor > fodder
• OE ūder > udder

There are of course many inherited Germanic words ending in -nder, such as under and tinder (I can find no evidence of variants ending in -nther for words like this). There are also words ending in a vowel plus -der that are not inherited from Old English; mainly Middle English borrowings from French, such as cedar, cider and powder. Interestingly, the Oxford English dictionary attests variants spelled with th (such as sither, pouther) for some of these words. It also lists garthen as a Middle English spelling variant of garden, maþen as a pre-17 variant of maiden, and fardin(g) as a variant of farthing.

The adjective sodden comes from an Old English past participle that had d (soden) but other forms of the verb had þ (the infinitive was sēoþan, and the corresponding modern verb is seethe). Possibly because of this, forms like soþen, sothen are attested for the adjective in Middle English.

Another relevant word is heather (the etymology is unclear, but variants with d are attested).

Transcription note: for my transcriptions of Old English words here (the ones not in quotes) I normalized ð to þ (to standardize notation and avoid confusion with the phone [ð] and phoneme /ð/)

There are a few misconceptions in this question, and some speculated sound changes that never took place.

/d/ -> /ð/ in English

The first change you mention, changing /d/ into /ð/ in English, is not a shift that has ever taken place in English.

The First Germanic Sound Shift (also known as either Grimm’s Law or Rask’s Rule after the two linguists who independently discovered it around the same time) is responsible for the change of inherited Proto-Indo-European (PIE) *t to Proto-Germanic *þ, except if the stress was on the immediately following syllable, in which case, it went to *ð (as in *faðḗr, from *patḗr).

In the earlier stages of English, this /ð/ was often represented by ‹d›, just because spelling in earlier stages of literature was not particularly phonemic or precise.

But the sound shift itself took place at a time before there was anything that could be called ‘English’. By the time of English, the sound was already /ð/.

/ð/ -> /d/ in English

While it is true that there is great variation in how people pronounce /ð/, it is nonetheless a phoneme in English, and one that has largely been kept distinct from /d/.

Naturally, in some circumstances, an original /ð/ can be expected to turn more or less reliably to /d/. /nð/, for example, is quite likely to turn to /nd/. But in ‘regular’ circumstances, /d/ and /ð/ have remained distinct and separate in English.

The two words you cite, murder and burden, did indeed start out with an /ð/, but the reason they now have /d/ is most likely due to influence from Anglo-Norman, which did not have /ð/ at all. There is some evidence that consistently conflating /d/ and /ð/ was a trait of some dialects a few centuries later, but that is not necessarily related at all—and it was seemingly consistent, which is exactly what sound changes are. There may have been a stage or a dialect when/where /rð/ went to /rd/, and this may have been a contributing factor to why we now don’t say murther and burthen (except poetically and something to do with ships); but it was not a sound shift that affected English as a whole.

In Old German, /ð/ did indeed go to /d/, but it did so throughout the language. This clearly did not happen in English.

So in short:

1. When did this consonant shift happen in English?

   It didn’t; not really.

2. What are some more examples of the /ð/ → /d/ in English words?

   Apart from old dialectal forms, I can’t think of any. I’m sure there are some here and there, but off the top of my head, I can’t think of one.

3. How is the shift mirrored in other Germanic languages?

   It isn’t, since it’s not a real shift.