dyskinesia, dyskinetic, dyscinesia, dyscinetic 1. A defect in the ability to perform voluntary movement. 2. A class of diseases in which voluntary motion is impeded or handicapped. 3. Distortion of voluntary movements; involuntary muscular activity such as a tic, spasm, or myoclonus. Found on http://www.wordinfo.info/words/index/info/view_unit/1124/4