/ Dictionary / Index T trimethoprim: Meaning and Definition of Find definitions for: tri•meth•o•prim Pronunciation: (trī-meth'u-prim), [key] — n. Pharm. a synthetic crystalline compound, CHNO, usually combined with a sulfonamide as an antibiotic preparation in the treatment of urinary tract infections and pneumocystis pneumonia. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. trimethadione trimethylene Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language