orchestra

noun

1. A large group of musicians who play together on various instruments, usually including some from strings, woodwind, brass and/or percussion; the instruments played by such a group.

   “The orchestra plays music for the dancers to dance to in the 19th century-styled dance hall.”

   “It requires quite an orchestra to get a train to start; the guard blows his horn, the stationmaster rings a large bell, and the engine whistles.”

   “Musicians play their instruments. I play the orchestra.”

2. A semicircular space in front of the stage used by the chorus in Ancient Greek and Hellenistic theatres.
3. The area in a theatre or concert hall where the musicians sit, immediately in front of and below the stage, sometimes (also) used by other performers.