spontaneous

American  

[spon-tey-nee-uhs] / spɒnˈteɪ ni əs /

adjective

1. coming or resulting from a natural impulse or tendency; without effort or premeditation; natural and unconstrained; unplanned.

   a spontaneous burst of applause.

   Synonyms:

   free, unpremeditated

   Antonyms:

   premeditated

2. (of a person) given to acting upon sudden impulses.

3. (of natural phenomena) arising from internal forces or causes; independent of external agencies; self-acting.

4. growing naturally or without cultivation, as plants and fruits; indigenous.

5. produced by natural process.

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spontaneous British  

/ spɒnˈteɪnɪəs /

adjective

1. occurring, produced, or performed through natural processes without external influence

   spontaneous movement

2. arising from an unforced personal impulse; voluntary; unpremeditated

   a spontaneous comment

3. (of plants) growing naturally; indigenous

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Usage

What does spontaneous mean? Spontaneous means natural and unplanned. When you describe an action or event as spontaneous, it means it happened naturally, without having been planned, as in The meeting turned into a spontaneous dance party. When something that someone does is described as spontaneous, it means it was done out of a natural impulse, without having been thought about beforehandWhen spontaneous is used to describe a person, it means they have a tendency to or are known for doing things impulsively and without planning. This is usually used in a positive way to portray them as a fun person who is adventurous and willing to do things on the spur of the moment. Telling someone to be more spontaneous means you want them to be more flexible and willing to do more things on a whim instead of needings for things to be completely structured or scheduled. The state or quality of being spontaneous is spontaneity. In a scientific context, spontaneous is used to describe effects that happen independently, without being acted on by outside forces. The most well-known example of its use in this sense is in the term spontaneous combustion, in which something catches on fire due to an internal chemical reaction (as opposed to external ignition). Example: Julian’s friends knew him as a spontaneous guy who was always up for going on random adventures.

Related Words

See automatic, voluntary.

Other Word Forms

• nonspontaneous adjective
• nonspontaneousness noun
• semispontaneous adjective
• semispontaneousness noun
• spontaneously adverb
• spontaneousness noun
• subspontaneous adjective
• subspontaneousness noun
• unspontaneous adjective
• unspontaneousness noun

Etymology

Origin of spontaneous

First recorded in 1650–60; from Late Latin spontāneus, equivalent to Latin spont(e) “willingly” + -āneus ( -ān(us) -an + -eus -eous )

Explanation

Something spontaneous happens when you're least expecting it. Spontaneous things are natural or instinctive, and they happen without warning. If you plan to go to a movie and then you go, that's not a spontaneous thing. Ditching the movie at the last minute to go to the park? That's spontaneous. Spontaneous things happen all of a sudden, on the spur of the moment, without being planned. Spontaneous can also refer to things that happen without outside influence. Your parents will be happy if you do your chores spontaneously instead of waiting till they nag you.

Example Sentences

They quickly return to a lower energy state by releasing light at a specific frequency, a process known as spontaneous emission.

From Science Daily • Apr. 10, 2026

This one-sided empathy is not a spontaneous response to compelling facts, however.

From Slate • Apr. 3, 2026

Vance, though, is clearly incapable of such a spontaneous response.

From Salon • Apr. 1, 2026

You can hear people shouting and drinking and having a good time, and the crowd work is also a little more spontaneous and fun than it would be in a regular venue.

From Los Angeles Times • Mar. 27, 2026

The first spontaneous explosion took place in Soweto on the afternoon of Wednesday, June 16, 1976, where about ten thousand students marched through the dirt streets of Soweto protesting the Afrikaans decree.

From "Kaffir Boy: An Autobiography" by Mark Mathabane

Related Words

• casual
• impromptu
• instinctive
• offhand
• simple
• unplanned
• voluntary