mainpiece/ˈmeɪnpis/EtymologyFrom main + piece.nounThe primary play or other work performed at an evening's entertainment at the theatre, as opposed to smaller introductory or additional works.“A typical evening at the principal Dublin theatres could extend over five or six hours and consisted of a mainpiece, frequently with a prologue and epilogue, followed by one, and occasionally two, afterpieces.”The principal part of a ship's head; the principal piece of timber in a rudder.