/ Dictionary / Index D deltoid: Meaning and Definition of Find definitions for: del•toid Pronunciation: (del'toid), [key] — n. a large, triangular muscle covering the joint of the shoulder, the action of which raises the arm away from the side of the body. —adj. pertaining to or involving the deltoid. in the shape of a Greek capital delta (&Dgr;); triangular. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: deltoid (Thesaurus) deltiology deltoidal Related Content Daily Word Quiz: eureka Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language