definition of
triad

[1] #1 triad n. [three, 3, III, trio, threesome, tierce, leash, troika, trine, trinity, ternary, ternion, triplet, tercet, terzetto, trey, deuce-ace] the cardinal number that is the sum of one and one and one. wn

[2] #2 triad n. [trio, triplet, triple] a set of three similar things considered as a unit. wn

[3] #3 triad n. [trio, threesome, trinity] three people considered as a unit. wn

[4] #4 triad n. [common chord] a three-note major or minor chord; a note and its third and fifth tones. wn