spontaneous

adjective spon·ta·ne·ous \spän-ˈtā-nē-əs\

: done or said in a natural and often sudden way and without a lot of thought or planning

: doing things that have not been planned but that seem enjoyable and worth doing at a particular time

Full Definition of SPONTANEOUS

: proceeding from natural feeling or native tendency without external constraint

: arising from a momentary impulse

: controlled and directed internally : self-acting <spontaneous movement characteristic of living things>

: produced without being planted or without human labor : indigenous

: developing or occurring without apparent external influence, force, cause, or treatment

: not apparently contrived or manipulated : natural

— spon·ta·ne·ous·ly adverb

— spon·ta·ne·ous·ness noun

See spontaneous defined for English-language learners

See spontaneous defined for kids

Examples of SPONTANEOUS

Shane has a lovely habit of paying us spontaneous visits: one time she brought over a jar of a pickle she'd recently put up; another time just a good story or two. —James Oseland, Saveur, December 2006
Cold viruses can damage the olfactory system directly. This loss of smell may last even after the cold is over. Sometimes the sense comes back as suddenly as it disappeared, perhaps because even as adults we generate new olfactory neurons. Spontaneous improvement might be a person's best hope, because there are no real proven treatments for reversing olfactory nerve damage. —Harvard Health Letter, September 2001
Peter Jakobsen of the European Space Agency, which built the Faint Object Camera, drew spontaneous applause at the January meeting when he showed an image of supernova SN1987A from the instrument. —Kristin Leutwyler, Scientific American, March 1994
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Origin of SPONTANEOUS

Late Latin spontaneus, from Latin sponte of one's free will, voluntarily

First Known Use: 1653

Related to SPONTANEOUS

Synonyms: instinctive, instinctual, involuntary, knee-jerk, mechanic, mechanical, robotic, automatic

Antonyms: nonmechanical

Synonym Discussion of SPONTANEOUS

spontaneous, impulsive, instinctive, automatic, mechanical mean acting or activated without deliberation. spontaneous implies lack of prompting and connotes naturalness <a spontaneous burst of applause>. impulsive implies acting under stress of emotion or spirit of the moment <impulsive acts of violence>. instinctive stresses action involving neither judgment nor will <blinking is an instinctive reaction>. automatic implies action engaging neither the mind nor the emotions and connotes a predictable response <his denial was automatic>. mechanical stresses the lifeless, often perfunctory character of the response <a mechanical teaching method>.