1.a round or oval building without a roof that has a central open space surrounded by tiers of seats, especially one used by the ancient Romans for public entertainments
2.a large enclosure where sporting activities or public entertainments take place
3.a gallery of seats arranged in semicircular tiers for the audience in a theater or lecture room
4.a lecture hall or operating room where seating is arranged in semicircular tiers
5.a large circular building without a roof and with rows of seats that slope up and away from a central area, used for entertainments such as sports competitions or plays
amphitheaters