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.

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

Though Mr. Vile plays many of the instruments, the tracks feel communal, intimate and spontaneous.

From The Wall Street Journal • Jun. 2, 2026

Base told Rolling Stone in a 2014 interview the song's creation was spontaneous and he was shocked by its success.

From BBC • May 23, 2026

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

From Science Daily • May 10, 2026

Not only that, he said, but there had been no new examples of “so-called spontaneous transformed human cell cultures” since.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot

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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