/ Dictionary / Index T triad: Meaning and Definition of Find definitions for: tri•ad Pronunciation: (trī'ad, -ud), [key] — n. a group of three, esp. of three closely related persons or things. an element, atom, or group having a valence of three. Cf. monad (def. 2), dyad (def. 3). a group of three closely related compounds or elements, as isomers or halides. a chord of three tones, esp. one consisting of a given tone with its major or minor third and its perfect, augmented, or diminished fifth. (cap.) the three categories of strategic-nuclear-weapons delivery systems: bombers, land-based missiles, and missile-firing submarines. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: triad (Thesaurus) triacontanol triadelphous Related Content Daily Word Quiz: verdant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language