spon ‧ ta ‧ ne ‧ ous /spɒnˈteɪniəs $ spɑːn-/ BrE AmE adjective
[ Date: 1600-1700 ; Language: Late Latin ; Origin: spontaneus , from Latin sponte 'of your own free will' ]
1 . something that is spontaneous has not been planned or organized, but happens by itself, or because you suddenly feel you want to do it:
The crowd gave a spontaneous cheer.
My spontaneous reaction was to run away.
2 . someone who is spontaneous does things without planning them first – used to show approval
—spontaneously adverb :
She laughed spontaneously.
—spontaneity /ˌspɒntˈniːəti, ˌspɒntˈniːɪti, -ˈneɪəti $ ˌspɑːn-/ noun [uncountable]