<p><strong>Noun</strong></p><ul><li>A group of three, especially of three closely related persons or things.</li><li>Chemistry: an element, atom, or group having a valence of three. Compare monad (def 2), dyad (def 3).</li><li>A group of three closely related compounds or elements, as isomers or halides.</li><li>Music: a chord of three tones, especially one consisting of a given tone with its major or minor third and its perfect, augmented, or diminished fifth.</li><li>Triad, Military: the three categories of delivery systems for strategic nuclear weapons, namely bombers, land-based missiles, and missile-firing submarines. The report says this missile is required in order to sustain an effective air leg of the Triad.</li></ul><p><strong>End of Response</strong></p>