1.NounA 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."
2.NounA semicircular space in front of the stage used by the chorus in Ancient Greek and Hellenistic theatres.
3.NounThe 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.