Open English Wordnet
Adjectives
(a)involuntary, nonvoluntary, unvoluntarynot subject to the control of the will“involuntary manslaughter”, “involuntary servitude”, “an involuntary shudder”, “It (becoming a hero) was involuntary. They sank my boat” (John F.Kennedy)
(a)involuntarycontrolled by the autonomic nervous system; without conscious control“involuntary muscles”, “gave an involuntary start”