DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   mocker
       n 1: someone who jeers or mocks or treats something with
            contempt or calls out in derision [syn: scoffer,
            flouter, mocker, jeerer]
       2: long-tailed grey-and-white songbird of the southern United
          States able to mimic songs of other birds [syn:
          mockingbird, mocker, Mimus polyglotktos]