- (n.) A coalition or union of two vowel sounds pronounced in one syllable; as, ou in out, oi in noise; -- called a proper diphthong.
- (v.t.) To form or pronounce as a diphthong; diphthongize.
- (n.) 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.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). diphthong. Retrieved September 21, 2026, from http://smartdefine.org/diphthong/definitions/1997872 |
| Chicago | Webster's. 2011. "diphthong" http://smartdefine.org/diphthong/definitions/1997872 (accessed September 21, 2026). |
| Harvard | Webster's 2011, diphthong, Smart Define, viewed 21 September, 2026, <http://smartdefine.org/diphthong/definitions/1997872>. |
| MLA | Webster's. "diphthong" 27 May 2011. Web. 21 September 2026. <http://smartdefine.org/diphthong/definitions/1997872> |