Synonyms of spontaneous in English:

spontaneous


See US English definition of spontaneous

See UK English definition of spontaneous

See Spanish definition of espontáneo

adjective

1‘a spontaneous display of affection’

SYNONYMS
unforced, voluntary, unconstrained, unprompted, unbidden, unsolicited, unplanned, unpremeditated, unrehearsed, impulsive, impetuous, unstudied, impromptu, spur-of-the-moment, extempore, extemporaneous
unschooled, untaught, uninstructed
informal off-the-cuff
ANTONYMS

planned, forced, calculated

2‘a spontaneous reaction to danger’

SYNONYMS
reflex, automatic, knee-jerk, involuntary, unthinking, unconscious, instinctive, instinctual
informal gut
ANTONYMS

conscious

3‘she seems friendly and spontaneous’

SYNONYMS
natural, uninhibited, relaxed, unselfconscious, unaffected, easy, free and easy
impulsive, impetuous
open, genuine
ANTONYMS

inhibited