orchestra

Concise Oxford English Dictionary © 2008 Oxford University Press:
orchestra/ˈɔːkɪstrə/

▶noun

• 1 [treated as sing. or pl.] a group of instrumentalists, especially one combining string, woodwind, brass, and percussion sections.

• 2 (also orchestra pit) the part of a theatre where the orchestra plays, typically in front of the stage and on a lower level.

• 3 N. Amer. the stalls in a theatre.

• 4 the semicircular space in front of an ancient Greek theatre stage where the chorus danced and sang.

– derivatives
orchestral adjective,
orchestrally adverb.

– origin C17: via L. from Gk orkhēstra, from orkheisthai ‘to dance’.