/ Dictionary / Index T trimonthly: Meaning and Definition of Find definitions for: tri•month•ly Pronunciation: (trī-munth'lē), [key] — adj. occurring, taking place, done, or acted upon every three months. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. trimolecular trimorph Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language