Theater

noun

1. A place or building, consisting of a stage and seating, in which an audience gathers to watch plays, musical performances, public ceremonies, and so on.
2. A region where a particular action takes place; a specific field of action, usually with reference to war.

   "His grandfather was in the Pacific theater during the war."

3. A lecture theatre.
4. An operating theatre or locale for human experimentation.

   "This man is about to die, get him into theater at once!"

5. A cinema.

   "We sat in the back row of the theater and threw popcorn at the screen."