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.

Made with soft, cushiony materials, the doll also makes spontaneous requests, asking users to pat its head, hold its hand or share snacks with it, although it cannot eat.

From Barron's • Jun. 11, 2026

He took up the spontaneous change in assignment because he "wanted to earn some extra money", HTA manager Angfurba Sherpa tells the BBC.

From BBC • Jun. 10, 2026

They also showed stronger protection against spontaneous tumors and chemically induced skin cancer.

From Science Daily • May 10, 2026

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

From Salon • May 7, 2026

Departing from Goedart’s example, she also included eggs, declaring boldly that eggs were the source of every caterpillar despite widespread public belief in spontaneous generation of insects.

From "The Girl Who Drew Butterflies: How Maria Merian's Art Changed Science" by Joyce Sidman

Vocabulary lists containing spontaneous

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