noun Etymology: tri- + -phthong (as in diphthong) Date: circa 1599 a phonological unit consisting of three successive vocalic sounds in one syllable, trigraph , ~al adjective
TRIPHTHONG
Meaning of TRIPHTHONG in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012