tri·ad 
(trīăd′, -əd)
(trīăd′, -əd)n.
1. A group of three.
2. Music A chord of three tones, especially one built on a given root tone plus a major or minor third and a perfect fifth.
3. A section of a Pindaric ode consisting of the strophe, antistrophe, and epode.
[Late Latin trias, triad-, from Greek, the number three; see trei- in the Appendix of Indo-European roots.]
tri·adic (trī-ădĭk) adj.
triadleft to right: C major, E minor, and D diminished triads
- Indo-European root: pezd-
- Indo-European root: plat-
- Indo-European root: plek-
- Indo-European root: pleu-
- Indo-European root: plāk-
- Indo-European root: plāk-
- Indo-European root: pneu-
- Indo-European root: porko-
- Indo-European root: poti-
- Indo-European root: prek-
- Indo-European root: preus-
- Indo-European root: prī-
- Indo-European root: pā-
- Indo-European root: pāl-
- Indo-European root: pē(i)-
- Indo-European root: pō(i)-
- Indo-European root: pū̆-
- Indo-European root: pəter-
- Indo-European root: re-
- Indo-European root: reg-
- Indo-European root: rei-
- Indo-European root: reidh-
- Indo-European root: reig-
- Indo-European root: rep-
- Indo-European root: ret-