Triph'thong, n.

(trĭf'thong, or trĭp'thong) (Synop., § 130), n. [Fr. triphthongue, from Gr. τρι and φθογγή, φθόγγος, the voice, a sound.] (Pron.) A combination of three vowels in a single syllable, forming a simple or compound sound; a union of three vowel characters, representing together a single sound, as ieu in adieu, eau in beau, eye, and the like; a trigraph.