DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   pacer
       n 1: a horse used to set the pace in racing [syn: pacer,
            pacemaker, pacesetter]
       2: a horse trained to a special gait in which both feet on one
          side leave the ground together