Definition of "spontaneous"
adjective
comparative more spontaneous, superlative most spontaneous
Produced without being planted or without human cultivation or labor.
Quotations
H]e persisted in his design; and, because he would not make his wants known, actually subsisted for several days on hips, haws and sloes, and other spontaneous fruits which he gathered in the woods and fields.
1751, [Tobias] Smollett, chapter 106, in The Adventures of Peregrine Pickle […], volume IV, London: Harrison and Co., […]