Origin: Latin suffix -ary
Involuntary has 3 different meanings across 1 category:
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"
controlled by the autonomic nervous system; without conscious control
"involuntary muscles"
"gave an involuntary start"
Without intention; unintentional.
"The coffee spilled from her cup when she had an involuntary reaction to the sudden noise."
The word comes from the prefix in- combined with voluntary, originating from the Late Latin term involuntarius. It originally meant "not willing" or "against one's will."