Great Vowel ShiftGreat Vowel Shift
the complex series of sound developments (c. 1400 to c. 1750) which changed the vowel system of Middle English into that of Modern English: Middle English long high vowels (? and ?) changed to Modern English diphthongs (? and ?), and long mid and low vowels (?, ?, and ä) were raised in their tongue positions to the Modern English sounds (?, ?, and ?), but the orthography remained largely the same
Great Vowel Shift
A series of phonetic changes occurring in Early Modern English in which the Middle English low and mid long vowels were raised, (&adie;) and (&omacron;) becoming (a) and (&oomac;), for example, while the high long vowels (&emacron;) and (&oomac;) became the diphthongs (&imacron;) and (ou).