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v. Simple past tense and past participle of diphthongize.

"To people outside of NZ and Australia, the two accents sound very similar, but NZers and Australians themselves are hyper-aware of the admittedly quite few really clear markers of difference, such as the vowel in "fish", the vowel in "red" and the vowels like in "bead" that for Australians are often diphthongized."

diphthongized    diphthongizing   

change    switch    shift   

monophthongize   

break