an edifice in which dramatic performances or spectacles are exhibited for the amusement of spectators; anciently uncovered, except the stage, but in modern times roofed.-any room adapted to the exhibition of any performances before an assembly, as public lectures, scholastic exercises, anatomical demonstrations, surgical operations, etc.-that which resembles a theater in form, use, or the like; a place rising by steps or gradations, like the seats of a theater.-a sphere or scheme of operation.-a place or region where great events are enacted; as, the theater of war.