triumvirate

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, […]

[H]e frets / That Lepidus of the Triumpherate, ſhould be depos'd, / And being that, vve detaine all his Reuenue.

Any group of three joint rulers.

Then vvas contriued a petition, as from the generalitie, vnto the triumuirat Gouernors; vvherein they ſupplicated, that by no meanes they ſhould reſigne the gouernment to any ſhould come from England, vpon vvhat tearmes ſoeuer, vntill ſix moneths after the returne of their ſhip ſent to the VVeſt-Indies: […]

Any group of three people regarded as significant in some way; also (rare), a group of three things; a trio.

I have therefore alvvayes endevoured to compoſe thoſe fevvds and angry diſſentions betvveene affection, faith, and reaſon. For there is in our ſoule a kind of Triumvirate, or triple government of three competitors, vvhich diſtract the peace of this our Common-vvealth, not leſſe than did that other the State of Rome.

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