amphitheatre
/ˈæmfɪˌθɪətə(r)/(美 amphitheater)
noun
1- (especially in Greek and Roman architecture) a round building, typically unroofed, with a central space for the presentation of dramatic or sporting events surrounded by tiers of seats for spectators（尤指希腊和罗马建筑）圆形露天剧场; 圆形露天竞技场。
1.1
- a semicircular seating gallery in a theatre（剧院）半圆形楼座。
词源
late Middle English: via Latin from Greek amphitheatron, from amphi 'on both sides' + theatron （see THEATRE）.