triumvirate

noun3

1. •
   Any group of three joint rulers.
2. •
   (historical) A council of three magistrates ruling jointly; specifically, the First Triumvirate (60 or 59 – 53 B.C.E.) or the Second Triumvirate (43 – 33 or 27 B.C.E.); the office of a triumvir (“one of such magistrates”), or of the three triumviri.

   • […] I must not forget to set dovvne a pretie jest, vvhich hath been reported by many as touching Lepidus: It happened during the time of his Triumvirat, […] — 1601
3. •
   (figurative) Any group of three people regarded as significant in some way; also (rare), a group of three things; a trio.

   • VVhen Johnson [Ben Jonson], [William] Shakespeare, and thy selfe [John Fletcher] did sit, / And svvay'd in the Triumvirate of vvit— […] — 1647