Iotacism


 * For the palatalization of certain consonants in Slavic languages, see iotation.

Iotacism is the process by which a number of vowels and diphthongs in Ancient Greek converged their pronunciation to sound like iota in Modern Greek.

Instances of iotacism
Ancient Greek had a broader range of vowels (see Ancient Greek phonology) than Modern Greek. Eta (η) was a long open-mid front unrounded vowel, and upsilon (υ) was a close front rounded vowel. Over the course of time, both of these vowels came to be pronounced like the close front unrounded vowel iota (ι). In addition, certain diphthongs merged to the same pronunciation, especially epsilon-iota (ει) and (later) upsilon-iota (υι).

Issues in textual criticism
Iotacism meant that some words with originally distinct pronunciations were pronounced similarly, which can be seen in some of the variant readings of the New Testament. For example, in a few places "you" (or "your") is substituted for "we" (or "our"), or vice versa; the upsilon of ὑμεις humeis (or ὑμων humōn) and the eta of ἡμεις hēmeis (or ἡμων hēmōn) could be easily confused if a lector were reading to copyists in a scriptorium. As an example of a relatively minor (almost insignificant) source of "variant readings", some ancient manuscripts spelled words the way they sounded, such as the 4th-century Codex Sinaiticus, which regularly substitutes a plain iota for the epsilon-iota diphthong.