Term applied to operas with comparatively small no. of singers and orch. players, e.g. Britten's The Rape of Lucretia and The Turn of the Screw, but there is no question of such works being perf. in a room instead of a th. R. Strauss's Ariadne auf Naxos is strictly a chamber opera, but is perf. at CG, NY Met, and Vienna State Opera.