1. a building where theatrical performances or motion-picture shows can be presented

e.g. the house was full

Synonym: theaterhouse

2. the art of writing and producing plays

Synonym: dramaturgydramatic artdramaticstheater

3. a region in which active military operations are in progress

e.g. the army was in the field awaiting action
he served in the Vietnam theater for three years

Synonym: fieldfield of operationstheatertheater of operationstheatre of operations