a union of three vowels (letters or sounds) pronounced in one syllable (as in fire) 三合元音。 与diphthong, monophthong相对 ■three written vowel characters representing the sound of a single vowel (as in beau) (表示一个元音的)三元音字母(如beau)
派生 triphthongal adjective 语源
mid 16th cent.: from French triphtongue, from tri- 'three', on the pattern of diphthong