Longman Dictionary of Contemporary English - theatre

~ BrE theater AmE n 1 »BUILDING« a building or place with a stage where plays are performed  (an open-air theatre | the Mercury Theater) 2 »PLAYS« a) plays as a form of entertainment  (I enjoy theater and swimming. | the theatre)  (He's really interested in literature and the theatre. | good theatre (=effective entertainment))  (Yeats' plays are great poetry but they are not good theatre.) b) the work of acting in, writing, or organizing plays  (classes in theater and music | She's been working in the theatre for over thirty years.) 3 »IN A HOSPITAL« a special room in a hospital where medical operations are done; operating theatre BrE 4 »AREA« a large area where a war is being fought  (the Pacific theater during World War II) 5 »PLACE TO SEE A FILM« AmE, AustrE a building where films are shown; cinema (1) BrE; movie theater AmE