The Collaborative International Dictionary of English v.0.48:

Choir \Choir\, n. [OE. quer, OF. cuer, F. ch[oe]ur, fr. L.
   chorus a choral dance, chorus, choir, fr. Gr. ?, orig.
   dancing place; prob. akin to ? inclosure, L. hortus garden,
   and E. yard. See Chorus.]
   1. A band or organized company of singers, especially in
      church service. [Formerly written also quire.]
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   2. That part of a church appropriated to the singers.
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   3. (Arch.) The chancel.
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   Choir organ (Mus.), one of the three or five distinct
      organs included in the full organ, each separable from the
      rest, but all controlled by one performer; a portion of
      the full organ, complete in itself, and more practicable
      for ordinary service and in the accompanying of the vocal
      choir.

   Choir screen, Choir wall (Arch.), a screen or low wall
      separating the choir from the aisles.

   Choir service, the service of singing performed by the
      choir. --T. Warton.
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