The Collaborative International Dictionary of English v.0.48:

Cockhorse \Cock"horse`\, n.
   1. A child's rocking-horse.
      [1913 Webster]

            Ride a cockhorse to Banbury cross.    --Mother
                                                  Goose.
      [1913 Webster]

   2. A high or tall horse. [R.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cockhorse \Cock"horse`\, a.
   1. Lifted up, as one is on a tall horse.
      [1913 Webster]

   2. Lofty in feeling; exultant; proud; upstart.
      [1913 Webster]

            Our painted fools and cockhorse peasantry.
                                                  --Marlowe.
      [1913 Webster]

WordNet (r) 3.0 (2006):

cockhorse
    n 1: anything used as a toy horse (such as a rocking horse or
         one knee of an adult)