Definify.com
Webster 1913 Edition
Monophthong
Mon′oph-thong
,Noun.
[Gr. [GREEK] with one sound;
μόνοσ
alone + [GREEK] sound, voice.] 1.
A single uncompounded vowel sound.
2.
A combination of two written vowels pronounced as one; a digraph.
Webster 1828 Edition
Monophthong
MON'OPHTHONG
,Noun.