What does involuntary mean?
Involuntary describes an action, reaction, or bodily process that occurs without conscious intention or deliberate control. It is especially common in medical and physiological contexts, as in involuntary muscle contractions, but it can also describe laughter, a smile, a response to an unexpected event, or conduct that a person did not consciously choose. The word is more precise than merely saying that something was accidental, because it often suggests an automatic or uncontrollable response. In legal and everyday usage, it may also describe an act performed without intention, although specific legal terms can carry additional defined meanings. The related noun is chiefly used for an unconsciously occurring muscular movement or reaction. Together, the adjective and noun describe the distinction between deliberate control and automatic bodily or mental responses.
Occurring or performed without conscious intention, choice, or deliberate control.
"The loud noise produced an involuntary flinch."
Often used for automatic bodily reactions, but also for actions or responses that a person did not mean or choose.
A bodily movement or physiological reaction that occurs without conscious initiation, especially a muscle twitch or spasm.
"The patient experienced an involuntary in her right hand."
Chiefly used in medical and neurological contexts.
The word involuntary literally means “not voluntary”: it describes everything the body or mind does without a conscious decision.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does involuntary come from?
Involuntary comes from Late Latin involuntarius, formed from the Latin prefix in-, meaning “not,” and voluntarius, meaning “willing” or “voluntary.” It entered English during the early 17th century and was initially used especially in medical contexts. The same Latin root voluntas, meaning “will,” underlies volunteer, voluntary, and volition.
Related word forms
How involuntary is actually used
The adjective is neutral in register and common in medical, psychological, legal, and general contexts. It describes conduct that is not deliberately chosen, but it does not necessarily imply that the result was accidental.
Easily confused with involuntary
An involuntary action occurs without conscious intention, whereas a voluntary action is performed deliberately and with control.