Diphthongises

Part of speech: verb

Definitions

1. Pronounces a single vowel sound as a gliding combination of two vowel sounds within one syllable, as in the vowel of the word price
2. Turns a simple vowel into a glide between two sounds in one syllable, so that the sound changes quality while it is being spoken
3. Makes a pure vowel into a blended sound that moves from one vowel position to another within a single syllable

Etymology: "Diphthongises" is the third-person singular form of "diphthongise", the British spelling of "diphthongize," meaning to turn a single vowel into a glide between two vowel sounds within one syllable. The verb is built from "diphthong," which comes from Late Latin "diphthongus," borrowed from Greek "diphthongos." The Greek word joins "di-," meaning "two," with "phthongos," meaning "sound" or "voice," so a diphthong is literally a "two-sound" vowel. The "-ise" ending is an ordinary English verb suffix, drawn from Greek and Latin "-izein" and "-izare," which turned nouns into verbs meaning "to make into" or "to treat in a certain way." Speakers apply it freely to scientific and phonetic terms, so "diphthongise" follows the same pattern as many other verbs formed from nouns.