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Synonyms for Spontaneous (same or very similar meaning)

WordNet sense 1 (unthinking; prompted by (or as if by) instinct):
instinctive, natural

WordNet sense 2 (happening or arising without apparent external cause):
self-generated

WordNet sense 3 (said or done without having been planned or written in advance):
ad-lib, unwritten

WordNet sense 4 (not furnished with or using a script):
unscripted


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