The Great Vowel Shift

The Great Vowel Shift is a phonetic change which occurred in English in the XIV—XV centuries.

The difference in pronunciation of long vowels is the main difference between ME and ModE. Before the GVS the pronunciation of vowels was much like that in Latin. However, during the Great Vowel Shift, the two highest long vowels became diphthongs, and the other five underwent an increase in tongue height with one of them coming to the front.

The principal changes (with the vowels shown in IPA) are roughly as follows.^[4] However, exceptions occur, the transitions were not always complete, and there were sometimes accompanying changes in orthography:

Middle English [aː] (ā) fronted to [æː] and then raised to [ɛː], [eː] and in many dialects diphthongised in Modern English to [eɪ] (as in m a ke). (The [a:] in the Middle English words in question had arisen earlier from lengthening of short a in open syllables and from French loan words, rather than from original Old English ā, because the latter had in the meantime been raised to Middle English [ɔː].)

Middle English [ɛː] raised to [eː] and then to modern English [iː] (as in b ea k).

Middle English [eː] raised to Modern English [iː] (as in f ee t).

Middle English [iː] diphthongised to [ɪi], which was most likely followed by [əɪ] and finally Modern English [aɪ] (as in m i ce).

Middle English [ɔː] raised to [oː], and in the eighteenth century this became Modern English [oʊ] or [əʊ] (as in b oa t).

Middle English [oː] raised to Modern English [uː] (as in b oo t).

Middle English [uː] was diphthongised in most environments to [ʊu], and this was followed by [əʊ], and then Modern English [aʊ] (as in m ou se) in the eighteenth century. Before labial consonants, this shift did not occur, and [uː] remains as in s ou p and r oo m (its Middle English spelling was roum).

This means that the vowel in the English word same was in Middle English pronounced [aː] (similar to modern psalm); the vowel in feet was [eː] (similar to modern fate); the vowel in wipe was [iː] (similar to modern weep); the vowel in boot was [oː] (similar to modern boat); and the vowel in mouse was [uː] (similar to modern moose).

The effect of the Great Vowel Shift may be seen very clearly in the English names of many of the letters of the alphabet. A, B, C and D are pronounced /eɪ, biː, siː, diː/ in today's English, but in contemporary French they are /a, be, se, de/. The French names (from which the English names are derived) preserve the English vowels from before the Great Vowel Shift. By contrast, the names of F, L, M, N and S (/ɛf, ɛl, ɛm, ɛn, ɛs/) remain the same in both languages, because "short" vowels were largely unaffected by the Shift.

Otto Esperson was the researcher o The GVS and suggested to name it THE GVS.