COLISEUM
amphitheater, amphitheatre, coliseum
(noun) an oval large stadium with tiers of seats; an arena in which contests and spectacles are held
Source: WordNet® 3.1
Etymology
Noun
coliseum (plural coliseums)
A large theatre, cinema, or stadium.
A large, often circular building, for indoor sporting events, exhibitions, concerts, etc.; arena.
Source: Wiktionary
Col`i*se"um, n. Etym: [NL. (cf. It. coliseo, colosseo), fr. L.
colosseus colossal, fr. colossus a colossus. See Colossus, and cf.
Colosseum.]
Definition: The amphitheater of Vespasian at Rome, the largest in the
world. [Written also Colosseum.]
Source: Webster’s Unabridged Dictionary 1913 Edition