2. music musical chord: a musical chord consisting of three notes, especially a chord made up of a tonic, a third, and a fifth
3. chemistry atom with valence of 3: an atom or chemical group with a valence of three
4. military U.S. strategic missile force: a U.S. strategic missile force made up of bombers, land-based ballistic missiles, and submarine-launched ballistic missiles
5. literature Welsh literary form: a form of composition in ancient Welsh literature in which subjects or statements are arranged in groups of three
[Mid-16th century. Via French triade or late Latin triad-< Greek triad- "three"]
