spontaneous

[spon-tey-nee-uhs] / spɒnˈteɪ ni əs /

ADJECTIVE

impulsive, willing

Synonyms

STRONGEST

casual impromptu instinctive offhand simple unplanned voluntary

WEAK

ad-lib automatic break loose down extemporaneous extempore free free-spirited from the hip impetuous improvised inevitable involuntary irresistible natural off top of head off-the-cuff unartful unavoidable unbidden uncompelled unconscious unconstrained uncontrived uncontrolled unforced unintentional unpremediated unprompted unsophisticated unstudied up front

Antonyms

STRONGEST

deliberate planned

WEAK

intended premeditated

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Most cancers are spontaneous and can’t be detected in a genetic test.

From Barron's • May 21, 2026

“She had a spontaneous unexplained brain bleed that led to brain death.”

From Salon • May 7, 2026

And what better indication of the demise of the spontaneous phone call can be found?

From The Wall Street Journal • May 1, 2026

Although they appear spontaneous, there is a level of coordination and predictability to them.

From BBC • Apr. 28, 2026

It is too well executed to be spontaneous, because it happens in complete unison.

From "Catching Fire" by Suzanne Collins

Vocabulary lists containing spontaneous

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