Diphthong

(dip'thong.) [From Gr. di, for dis,double, and pht hon gos, a voice.] (Gram.) A compound vowel, or 2vowels so united as to be pronounced in 1 syllable, as joint, mouse, . Some double vowels, however, afford exceptional cases, inasmuch as the sound of one vowel only is heard when the word of which they form a part is articulated; as niece, leave, and the like. [s. 289]