What does the term in theater mean in military talk?

Answer 1

The term 'In Theatre" refers to a large geographic area in which combat operations are occurring. For example in WW2, Americas fought in both the 'European Theatre' and the 'Pacific Theatre'. The term comes from "Theatre of Operations."

Answer 2

In a combat zone.

No. A "theater" in military terms is a large area of operations, geographically limited by some consideration (usually, political or natural feature boundaries). Thus, one would speak of the Southeast Asian Theater, which would encompass not just Vietnam, but Thailand, Laos, Cambodia, Burma and possible even southern China and Malaysia. Theaters are designated according to some commonality of political or military purpose, and are arbitrary designations (i.e. the scope of a theater can change depending on current events). Generally speaking, a theater is the largest distinct military command - that is, the commander of a military theater is not subordinate to any other operational commanders, only the political/military bureaucracy.

Thus, when someone speaks of something being "in theater", it means that the action or person or event happened inside the general area of the current theater of operations. That is, it's a geographical reference. It's used to distinguish things that probably have some immediate relevance to the person speaking vs. things happening elsewhere in the world.

Thus, one could say "General Bart just arrived in theater", indicating that General Bart was now in the area, and likely would be of immediate concern to others who would be working for him (vs possibly off in Washington for consultation). "The in theater OpTempo has increased over the last two weeks" would indicate that operations in this particular area have been increasing, but says nothing about what operations outside the theater are occurring.

Answer 3

It is another name for your area of operations.