The Collaborative International Dictionary of English v.0.48:
Chorus \Cho"rus\, n.; pl. Choruses. [L., a dance in a ring, a
dance accompanied with song; a chorus, a band of dancers and
singers. Gr. ?. See Choir.]
1. (Antiq.) A band of singers and dancers.
The Grecian tragedy was at first nothing but a
chorus of singers. --Dryden.
2. (Gr. Drama) A company of persons supposed to behold what
passed in the acts of a tragedy, and to sing the
sentiments which the events suggested in couplets or
verses between the acts; also, that which was thus sung by
What the lofty, grave tragedians taught
In chorus or iambic. --Milton.
3. An interpreter in a dumb show or play. [Obs.]
4. (Mus.) A company of singers singing in concert.
5. (Mus.) A composition of two or more parts, each of which
is intended to be sung by a number of voices.
6. (Mus.) Parts of a song or hymn recurring at intervals, as
at the end of stanzas; also, a company of singers who join
with the singer or choir in singer or choir in singing
7. The simultaneous of a company in any noisy demonstration;
as, a Chorus of shouts and catcalls.