D defs.my
Entry 3 senses Webster, 1913

Triad

/trī'-ădˌ/ · Tri·ad · IPA /ˈtɹaɪ.æd/
01 n. A union of three; three objects treated as one; a ternary; a trinity; as, a triad of deities.
  1. 1.
    A union of three; three objects treated as one; a ternary; a trinity; as, a triad of deities.
  2. 2.
    A chord of three notes.(Mus.)
  3. 3.
    An element or radical whose valence is three.(Chem.)
Phrases & compounds
Triads of the Welsh bards — poetical histories, in which the facts recorded are grouped by threes, three things or circumstances of a kind being mentioned together.
Hindu triad — See Trimurti.