Diphthong1. (n.) A union of two vowel sounds pronounced in one syllable; as, ou in out, oi in noise; -- called a proper diphthong.
2. (n.) 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.
3. (v. t.) To form or pronounce as a diphthong; diphthongize.
Thesaurus Entries
allophone, alveolar, apico-alveolar, apico-dental, articulation, aspiration, assimilation, bilabial, cacuminal, cerebral, check, consonant, continuant, dental, dissimilation, epenthetic vowel, explosive, glide, glottal, glottalization, guttural, labial, labialization, labiodental, labiovelar, laryngeal, lateral, lingual, liquid, manner of articulation, modification, monophthong, morphophoneme, mute, nasal, occlusive, palatal, parasitic vowel, peak, pharyngeal, pharyngealization, phone, phoneme, plosive, prothetic vowel, retroflex, segmental phoneme, semivowel, sonant, sonority, speech sound, stop, surd, syllabic nucleus, syllabic peak, syllable, transition sound, triphthong, velar, vocable, vocalic, vocoid, voice, voiced sound, voiceless sound, voicing, vowel