not voluntary; independent of one's will; not by one's own choice: an involuntary listener; involuntary servitude.
unintentional; unconscious: an involuntary gesture.
Physiology. acting independently of or done or occurring without volition: involuntary muscles.

Origin of involuntary

From the Late Latin word involuntārius, dating back to 1525–35. See in-3, voluntary
Related formsin·vol·un·tar·i·ly [in-vol-uhn-ter-uh-lee, -vol-uhn-tair-] /ɪnˈvɒl ənˌtɛr ə li, -ˌvɒl ənˈtɛər-/, adverbin·vol·un·tar·i·ness, noun

Synonyms for involuntary

Synonym study

1, 3. See automatic.

Antonyms for involuntary Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for involuntary

Contemporary Examples of involuntary

Historical Examples of involuntary

  • It was as though the involuntary kiss had lurched him forward into a futurity of misery.


    W. A. Fraser

  • A kind of net for effecting an involuntary change of environment.

  • The parson wrung his hands in an involuntary gesture of appeal.

    Tiverton Tales

    Alice Brown

  • She gave an involuntary look at the barn, where David was whistling a merry stave.

    Tiverton Tales

    Alice Brown

  • Again he had to control the involuntary movement of his left arm.

British Dictionary definitions for involuntary



carried out without one's conscious wishes; not voluntary; unintentional
physiol (esp of a movement or muscle) performed or acting without conscious control
Derived Formsinvoluntarily, adverbinvoluntariness, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for involuntary

mid-15c., from Late Latin involuntarius "involuntary," from in- "not, opposite of" (see in- (1)) + Latin voluntarius (see voluntary). Related: Involuntarily.

Online Etymology Dictionary, © 2010 Douglas Harper

involuntary in Medicine




Not subject to control of the volition.
Acting or done without or against one's will.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

involuntary in Science



Not under conscious control. Most of the biological processes in animals that are vital to life, such as contraction of the heart, blood flow, breathing, and digestion, are involuntary and controlled by the autonomic nervous system.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.