The Collaborative International Dictionary of English v.0.48:

Cocker spaniel \Cock"er span"iel\
   One of a breed of small or medium-sized spaniels kept for
   hunting or retrieving game or for household pets. They
   usually weigh from eighteen to twenty-eight pounds. They have
   the head of fair length, with square muzzle, the ears long
   and set low, the legs short or of medium length, and the coat
   fine and silky, wavy but not curly. Various colors are bred,
   as black, liver, red, black and white, black and tan, etc.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

cocker spaniel
    n 1: a small breed with wavy silky hair; originally developed in
         England [syn: cocker spaniel, English cocker spaniel,
         cocker]