The Collaborative International Dictionary of English v.0.48:

Choral \Cho"ral\, a. [LL. choralis, fr. L. chorus. See
   Chorus.]
   Of or pertaining to a choir or chorus; singing, sung, or
   adapted to be sung, in chorus or harmony.
   [1913 Webster]

   Choral service, a service of song.
      [1913 Webster] Choral

The Collaborative International Dictionary of English v.0.48:

Choral \Cho"ral\, chorale \chorale\, n. (Mus.)
   A stately hymn tune; a simple sacred tune, sung in unison by
   the congregation, used mostly in Protestant (especially
   Lutheran) churches; as, the Lutheran chorals. [Sometimes
   written chorale.]
   [1913 Webster + WordNet 1.5]

WordNet (r) 3.0 (2006):

choral
    adj 1: related to or written for or performed by a chorus or
           choir; "choral composition"; "choral ensemble"
    n 1: a stately Protestant (especially Lutheran) hymn tune [syn:
         chorale, choral]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "choral":
   alto, baritone, bass, bravura, choric, coloratura, dramatic,
   falsetto, heroic, hymnal, liturgical, lyric, operatic, psalmic,
   psalmodial, psalmodic, sacred, singing, soprano, tenor, treble,
   vocal