What does "diphthongize" mean?

To change to a diphthong, as by inserting or removing a vowel.

What is a synonym for "diphthongize"?

Common synonyms include: diphthongise.

Pronounced //ˈdɪfθɑŋaɪz//.

/ˈdɪfθɑŋaɪz/ verb

verb ·Rare ·Advanced level

Verb

1
To change to a diphthong, as by inserting or removing a vowel. transitive
"Some of these [monophthongs] will be diphthongised under the influence of following sounds."
2
change from a simple vowel to a diphthong wordnet
3
To become a diphthong. intransitive

"Some of these [monophthongs] will be diphthongised under the influence of following sounds."

From diphthong + -ize.