Great Vowel Shift
The Great Vowel Shift was a major change in the pronunciation of the English language that took place in England between 1350 and 1600. Through the Great Vowel Shift, all Middle English long vowels changed their pronunciation. English spelling was becoming standardized in the 15th and 16th centuries, and the Great Vowel Shift is responsible for many of the peculiarities of English spelling.
History of analysis
The Great Vowel Shift was first studied by Otto Jespersen (1860–1943), a Danish linguist and Anglicist, who coined the term.
Overall changes
The main difference between the pronunciation of Middle English in the year 1400 and Modern English is in the value of the long vowels. Long vowels in Middle English had "continental" values much like those in Italian and Standard German, but in standard Modern English they have entirely different pronunciations. This change in pronunciation is known as the Great Vowel Shift.
This timeline shows the main vowel changes that occurred between late Middle English in the year 1400 and Modern English in the mid-20th century, using representative words. The Great Vowel Shift occurred in the lower half of the table, between the years 1400 and 1600. The changes that happened after 1600 are not usually considered part of the Great Vowel Shift proper. Pronunciation is given in the International Phonetic Alphabet: