amphitheatre
Concise Oxford English Dictionary © 2008 Oxford University Press:
amphitheatre /ˈamfɪθɪətə(r)/ (US amphitheater)
▶noun an open, circular or oval building consisting of tiers of seats surrounding a central space for dramatic or sporting events.
■ a semicircular seating gallery in a theatre.
'amphitheatre' also found in these Oxford entries:

