1. changes a simple vowel sound into a diphthong or pronounces as a diphthong
Usage: linguistics; third person singular present

Examples

• The dialect diphthongizes the long ‘a’ sound in many words.
• She diphthongizes vowels when speaking quickly.
• This accent diphthongizes certain vowel sounds that are pure in other dialects.
• The speaker diphthongizes the ‘o’ in ‘boat’ more than usual.
• Regional speech often diphthongizes vowels differently than standard pronunciation.