From Longman Dictionary of Contemporary Englishspontaneousspon‧ta‧ne‧ous /spɒnˈteɪniəs $ spɑːn-/ ●○○ adjective 1 PLAN#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, -ˈneɪəti $ ˌspɑːn-/ noun [uncountable]
Examples from the Corpus
spontaneous• I'm trying to be more spontaneous.• The invitation was completely spontaneous.• Furthermore, once initiated, the combustion of methane gas at 25°C is very spontaneous.• The group was greeted by spontaneous applause.• The crowd gave a spontaneous cheer when the news was announced.• People believe that behaviour is best left to natural, spontaneous expression.• The isotope U-235 is unstable, decaying by a process called spontaneous fission.• an act of spontaneous generosity• There were songs and testimonies, spontaneous sermons and exhortations, joyous shouts and prayers punctuated by sobs and tears.• The way he told the story, it sounded as if both happened with raw, spontaneous simultaneity.• He suggests that whereas spontaneous speech invokes the child's own realisation rules, imitation does not.Origin spontaneous (1600-1700) Late Latin spontaneus, from Latin sponte “of your own free will” 