an oval or round building with tiers of seats around a central open area, as those used in ancient Rome for gladiatorial contests.

any similar place for public contests, games, performances, exhibitions, etc.; an arena, stadium, or auditorium.

a room having tiers of seats arranged around a central area, in which students and other observers can view surgery, hear lectures, etc.

British .

the first section of seats in the gallery of a theater.

a designated section of seats in any part of a theater.

a level area of oval or circular shape surrounded by rising ground.