The definition of spontaneous is unplanned or done on impulse.(adjective)
An example of spontaneous is waking up and deciding to take a trip across the country that day.
See spontaneous in Webster's New World College Dictionary
Origin: LL spontaneus < L sponte, of free will < IE base *(s)pen(d)-, to pull > spin
See spontaneous in American Heritage Dictionary 4
Origin: From Late Latin spontāneus, of one's own accord
Origin: , from Latin sponte; see (s)pen- in Indo-European roots.
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