diphthongise
/ˈdɪfθɔŋaɪz/
verb
- To pronounce a simple vowel as a diphthong (a gliding vowel sound).
- Some speakers diphthongise the vowel in 'face' so it sounds like 'fayce'.
- In certain accents, people diphthongise the 'o' in 'go' to sound like 'gow'.
- The teacher explained how to diphthongise vowels when learning a new language.