Definition of diphthong :
1. A coalition or union of two vowel sounds pronounced in one syllable; as, ou in out, oi in noise; - called a proper diphthong.
2. A vowel digraph; a union of two vowels in the same syllable, only one of them being sounded; as, ai in rain, eo in people; - called an improper diphthong.
3. To form or pronounce as a diphthong; diphthongize.
- But if a Diphthong precede the last Consonant, the Rhyme must begin at that Vowel of it whose Sound most prevails; as, Next to the Pow'r of waking Tempests cease, Was in that Storm to have so calm a Peace. - "The Art of English Poetry (1708)", Edward Bysshe.
- 6. What is a proper diphthong? - "The Grammar of English Grammars", Goold Brown.
- When two vowels meet together, and are joined in one syllable, they are called a diphthong. - "The Grammar of English Grammars", Goold Brown.