Diphthong
Diphthong (?; 115, 277) , noun
[Latin diphthongus, Greek {not transcribed}; di- = di`s- twice + {not transcribed} voice, sound, from {not transcribed} to utter a sound: compare French diphthongue.]
(a)
(Orthoepy) A coalition or union of two vowel sounds pronounced in one syllable; as, ou in out, oi in noise; -- called a proper diphthong.
(b)
(Orthoepy) A vowel digraph; a union of two vowels in the same syllable, only one of them being sounded; as, ai in rain, eo in people; -- called an improper diphthong.
Diphthong , transitive verb
To form or pronounce as a diphthong; diphthongize. [Rare]