Synonyms for spontaneous | Synonym.com

Synonyms for spontaneous

1. spontaneous (a.)

happening or arising without apparent external cause

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2. spontaneous abortion (n.)

a natural loss of the products of conception

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3. spontaneous combustion (n.)

ignition of a substance (as oily rags) resulting from an internal oxidation process

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4. ad-lib (s.)

said or done without having been planned or written in advance

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