What is the meaning of theater?

noun

• A building where theatrical performances or motion-picture shows can be presented.
  • usage: "the house was full"
  • synonyms: theatre, house
• The art of writing and producing plays.
  • synonyms: dramaturgy, dramatic art, dramatics, theatre
• A region in which active military operations are in progress.
  • usage: "the army was in the field awaiting action"; "he served in the Vietnam theater for three years"
  • synonyms: field, field of operations, theater of operations, theatre, theatre of operations