/ Dictionary / Index D diphthongize: Meaning and Definition of Find definitions for: diph•thong•ize Pronunciation: (dif'thông-īz", -gīz", -thong-, dip'-), [key] — v., -ized, -iz•ing. —v.t. to change into or pronounce as a diphthong. —v.i. to become a diphthong. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: diphthongize (Thesaurus) diphthongia diphycercal Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language