Synonyms of spontaneously in English:

spontaneously


See definition of spontaneously

adverb

1‘the huge crowd spontaneously broke into applause’

SYNONYMS
without being asked, of one's own accord, voluntarily, on impulse, impulsively, on the spur of the moment, extempore, extemporaneously
informal off the cuff

2‘he'd reacted spontaneously, displaying the full force of his anger’

SYNONYMS
without thinking, automatically, unthinkingly, involuntarily, instinctively