not 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
controlled by the autonomic nervous system; without conscious control; "involuntary muscles"; "gave an involuntary start"
something inverted in sequence or character or effect; "when the direct approach failed he tried the inverse"
reversed (turned backward) in order or nature or effect
opposite in nature or effect or relation to another quantity ; "a term is in inverse proportion to another term if it increases (or decreases) as the other decreases (or increases)"