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Showing results for spontaneous. Search instead for isooctanes.
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.

This one-sided empathy is not a spontaneous response to compelling facts, however.

From Slate • Apr. 3, 2026

This type of spontaneous movement has been linked to longevity in other species as well.

From Science Daily • Mar. 26, 2026

They want the gathering to feel casual, spontaneous — the sort of event where everyone simply appears with something charming and the table somehow assembles itself.

From Salon • Mar. 15, 2026

“Once everything had been signed off last night, there were lots of photos, lots of celebrating, and then a spontaneous outcry of ‘Aussie, Aussie, Aussie, oi, oi, oi’,” said Burke.

From The Wall Street Journal • Mar. 10, 2026

Thus one might think that the possibility of spontaneous proton decay could not be tested experimentally.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.