involuntary

adjective

in·​vol·​un·​tary (ˌ)in-ˈvä-lən-ˌter-ē 

-ˌte-rē

1

: done contrary to or without choice

2

: compulsory

3

: not subject to control of the will : reflex

involuntarily

(ˌ)in-ˌvä-lən-ˈter-ə-lē 

-ˈte-rə-

adverb

involuntariness

(ˌ)in-ˈvä-lən-ˌter-ē-nəs 

-ˌte-rē-

noun

Synonyms of involuntary

• accidental
• spontaneous
• unwilling
• unintentional
• forced
• coerced

Examples of involuntary in a Sentence

Breathing and circulation are involuntary processes.

When the door burst open, she let out an involuntary shriek.

The lawyer argued that the client's confession was involuntary.

Recent Examples on the Web

Days later, Kelley was placed on an involuntary 5150 hold at a Utah hospital due to a friend's concern for her mental health. —Liza Esquibias, PEOPLE, 3 Dec. 2025

The judge then ordered that Dear’s treatment go forward, and the involuntary medication started in April. —Shelly Bradbury, Denver Post, 25 Nov. 2025

Epilepsy is a chronic neurological disorder in which the brain produces recurring, unprovoked seizures – episodes of abnormal brain activity that cause involuntary changes in bodily function, sensations or awareness. —Daryl Austin, USA Today, 18 Nov. 2025

But this time, her son had a gun, and officers weren’t there to serve the involuntary commitment paperwork. —Charlotte Observer, 12 Nov. 2025

Word History

Etymology

Middle English involuntari, from Late Latin involuntarius, from Latin in- + voluntarius voluntary

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing involuntary

• involuntary manslaughter
• involuntary muscle

Rhymes for involuntary

• accretionary
• apothecary
• bicentenary
• certiorari
• concessionary
• concretionary
• confectionary
• confectionery
• constabulary
• contemporary
• deflationary
• depositary

Kids Definition

involuntary

adjective

in·​vol·​un·​tary (ˈ)in-ˈväl-ən-ˌter-ē 

1

: not made or done willingly or from choice : unwilling

2

: being enforced or required : mandatory

3

: not normally under the control of the will

an involuntary response to a stimulus

involuntarily

(ˌ)in-ˌväl-ən-ˈter-ə-lē 

adverb

Medical Definition

involuntary

adjective

in·​vol·​un·​tary (ˈ)in-ˈväl-ən-ˌter-ē 

: not subject to control of the will : reflex

involuntary contractions

Legal Definition

involuntary

adjective

in·​vol·​un·​tary in-ˈvä-lən-ˌter-ē 

: done, made, or initiated contrary to or without one's choice

an involuntary confession

an involuntary lien

an involuntary plaintiff joined in the action

involuntarily adverb