Amphitheatre vs. Theater — What's the Difference?

An amphitheatre (British English) or amphitheater (American English; both ) is an open-air venue used for entertainment, performances, and sports. The term derives from the ancient Greek ἀμφιθέατρον (amphitheatron), from ἀμφί (amphi), meaning "on both sides" or "around" and θέατρον (théātron), meaning "place for viewing".Ancient Roman amphitheatres were oval or circular in plan, with seating tiers that surrounded the central performance area, like a modern open-air stadium.

A building, room, or outdoor structure for the presentation of plays, films, or other dramatic performances.

An open, outdoor theatre (which may be a theatre in the round, or have a stage with seating on only one side), especially one from the classical period of ancient Greece or Rome, or a modern venue of similar design.

A room with tiers of seats used for lectures or demonstrations

(geology) A natural formation of a similar shape, where a steep mountain or slope a particular rock formation forms a partial or compete bowl, especially one used as a performance space (and possibly modified by carving out seats, etc) because the slopes naturally amplify or echo sound.

Dramatic literature or its performance; drama

A sloping gallery with seats for spectators (as in an operating room or theater)

The milieu of actors and playwrights.

An oval large stadium with tiers of seats; an arena in which contests and spectacles are held

The quality or effectiveness of a theatrical production

Dramatic material or the use of such material

The audience assembled for a dramatic performance.

A place that is the setting for dramatic events.

A large geographic area in which military operations are coordinated

A place or building, consisting of a stage and seating, in which an audience gathers to watch plays, musical performances, public ceremonies, and so on.

A region where a particular action takes place; a specific field of action, usually with reference to war.

A lecture theatre.

(medicine) An operating theatre or locale for human experimentation.

(US) A cinema.

Drama or performance as a profession or art form.

Any place rising by steps like the seats of a theater.

A conspicuous but unproductive display of action.

An edifice in which dramatic performances or spectacles are exhibited for the amusement of spectators; anciently uncovered, except the stage, but in modern times roofed.

Any room adapted to the exhibition of any performances before an assembly, as public lectures, scholastic exercises, anatomical demonstrations, surgical operations, etc.

That which resembles a theater in form, use, or the like; a place rising by steps or gradations, like the seats of a theater.

A sphere or scheme of operation.

A place or region where great events are enacted; as, the theater of war.

A building where theatrical performances or motion-picture shows can be presented;

The art of writing and producing plays

A region in which active military operations are in progress;