diphthongization

WordReference Random House Unabridged Dictionary of American English © 2026

diph•thong•ize  (dif′thông īz′, -gīz′, -thong-, dip′-), v., -ized, -iz•ing. [Phonet.]
v.t. 

1. Phonetics to change into or pronounce as a diphthong.

v.i. 

2. Phonetics to become a diphthong.

Also,[esp. Brit.,] diph′thong•ise′. 

• diphthong + -ize 1865–70

diph′thong•i•za′tion, n.