/ Dictionary / Index T triceps: Meaning and Definition of Find definitions for: tri•ceps Pronunciation: (trī'seps), [key] — pl. -ceps•es -ceps. a muscle having three heads or points of origin, esp. the muscle on the back of the arm, the action of which straightens the elbow. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: triceps (Thesaurus) tricentennial triceratops 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