Mock'er noun 1. One who, or that which, mocks; a scorner; a scoffer; a derider. 2. A deceiver; an impostor. 3. (Zoology) A mocking bird. Mocker nut (Botany) , a kind of hickory ( Carya tomentosa ) and its fruit, which is far inferior to the t... Found on http://www.encyclo.co.uk/webster/M/85