Definitions

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.

Spontaneous spending is likely to rise if the limit on contactless cards is increased or scrapped entirely, academics say.

From BBC • Sep. 13, 2025

Spontaneous mutations of DNA arise in all living cells, including those within bacteria.

From Science Daily • Nov. 16, 2024

Spontaneous offshoots of the established factions, such as the previously unknown Aqabat Jabr Battalion formed by the Awdat brothers and their friends, have proliferated.

From Reuters • Mar. 14, 2023

"Spontaneous miscarriage happens very, very frequently, especially in women who are older."

From Salon • Feb. 26, 2023

Napoleon had commanded that once a week there should be held something called a Spontaneous Demonstration, the object of which was to celebrate the struggles and triumphs of Animal Farm.

From "Animal Farm: A Fairy Story" by George Orwell

Vocabulary lists containing spontaneous

Essential Academic Vocabulary for High School Students, List 1

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100 Top "SAT" Words

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Animal Farm

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