The Collaborative International Dictionary of English v.0.48:

Pastorale \Pas`to*ra"le\, n. [It.]
   1. (Mus.) A composition in a soft, rural style, generally in
      6-8 or 12-8 time.
      [1913 Webster]

   2. A kind of dance; a kind of figure used in a dance.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pastorale
    n 1: a musical composition that evokes rural life [syn:
         pastorale, pastoral, idyll, idyl]