| Noun | 1. | theatre of operations - a region in which active military operations are in progress; "the army was in the field awaiting action"; "he served in the Vietnam theater for three years" armed forces, armed services, military, military machine, war machine - the military forces of a nation; "their military is the largest in the region"; "the military machine is the same one we faced in 1991 but now it is weaker" theater of war, theatre of war - the entire land, sea, and air area that may become or is directly involved in war operations region - a large indefinite location on the surface of the Earth; "penguins inhabit the polar regions" combat area, combat zone - a military area where combat forces operate |