D defs.my
Entry 2 senses Webster, 1913

Amphitheater

/ăm'-fəth-ē-āt'-ẽr/ · Am·phi·the·a·ter · IPA /ˈæmfəθiːˈeɪtər/
01 n. An oval or circular building with rising tiers of seats about an open space called the arena.
  1. 1.
    An oval or circular building with rising tiers of seats about an open space called the arena.
  2. 2.
    Anything resembling an amphitheater in form; as, a level surrounded by rising slopes or hills, or a rising gallery in a theater.