The Collaborative International Dictionary of English v.0.48:

Eclogue \Ec"logue\, n. [L. ecloga, Gr. ? a selection, choice
   extracts, fr. ? to pick out, choose out; 'ek out + ? to
   gather, choose: cf. F. ['e]gloque, ['e]cloque. See Ex-, and
   Legend.]
   A pastoral poem, in which shepherds are introduced conversing
   with each other; a bucolic; an idyl; as, the Ecloques of
   Virgil, from which the modern usage of the word has been
   established.

WordNet (r) 3.0 (2006):

eclogue
    n 1: a short poem descriptive of rural or pastoral life [syn:
         eclogue, bucolic, idyll, idyl]