spontaneous

adjective

spon·​ta·​ne·​ous spän-ˈtā-nē-əs 

1

: proceeding from natural feeling or native tendency without external constraint

2

: arising from a momentary impulse

3

: controlled and directed internally : self-acting

spontaneous movement characteristic of living things

4

: produced without being planted or without human labor : indigenous

5

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

6

: not apparently contrived or manipulated : natural

spontaneously adverb

spontaneousness noun

Did you know?

When English philosopher Thomas Hobbes penned his 1656 The Questions Concerning Liberty, Necessity, and Chance he included the following: "all voluntary actions … are called also spontaneous, and said to be done by man's own accord." Hobbes was writing in English, but he knew Latin perfectly well too, including the source of spontaneous; the word comes, via Late Latin spontaneus, from the Latin sponte, meaning "of one's free will, voluntarily." In modern use, the word spontaneous is frequently heard in more mundane settings, where it often describes what is done or said without a lot of thought or planning.

Synonyms

• automatic
• mechanical
• sudden
• reflex
• robotic
• instinctive
• mechanic
• simple

Choose the Right Synonym for 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

Examples of spontaneous in a Sentence

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

The comment was completely spontaneous.

He's a guy who's spontaneous and fun.

Recent Examples on the Web

These mutations can be spontaneous, but the paternal age of a sperm donor can also be a factor. —Chelsea Bailey, CNN Money, 25 Oct. 2025

The piece signals transformation, but the spontaneous laugh turns luxury into connection; by the red-gown reveal, the necklace reads less like a trophy and more like a charm that’s worked. —Lilah Ramzi, Vogue, 25 Oct. 2025

For the creation of wonderful characters and a story that feels spontaneous yet precise in its depiction of power, its moral dilemmas, and the absurd contradictions with the human condition. —Christian Blauvelt, IndieWire, 24 Oct. 2025

Baggy fits, soft fabrics, and thoughtful design make lounging, low-key workouts, or spontaneous errands feel effortless. —Katie Ann Lehman, StyleCaster, 24 Oct. 2025

Word History

Etymology

Late Latin spontāneus "voluntary, unconstrained" (from Latin sponte "of one's own accord, by one's own agency," ablative of *spons —of uncertain origin— + -āneus, suffix forming adjectives from temporal adverbs, from -ānus -an entry 2 + -eus -eous) + -ous

Note: The suffix -āneus, a joining of -ānus and -eus, occurs earlier with compound verbs (as consentāneus "agreeable, consentaneous," succīdāneus "killed as a substitute or addition"—see succedaneum) and phrasal derivatives (as circumforāneus "itinerant," mediterrāneus "remote from the coast, inland"). The earliest derivatives from temporal adverbs are subitāneus "happening without warning, sudden" (Seneca) and praesentāneus "immediately operative, prompt in effect" (in Seneca and Pliny).

First Known Use

1605, in the meaning defined at sense 1

Phrases Containing spontaneous

• spontaneous combustion
• spontaneous generation
• spontaneous recovery

Rhymes for spontaneous

• extraneous
• contemporaneous
• extemporaneous
• intracutaneous
• mucocutaneous
• lanius
• miscellaneous
• percutaneous
• simultaneous
• subcutaneous
• subterraneous
• transcutaneous

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Kids Definition

spontaneous

adjective

spon·​ta·​ne·​ous spän-ˈtā-nē-əs 

1

: done, said, or produced freely and naturally

spontaneous laughter

2

: acting or taking place without any outside force or cause

spontaneously adverb

spontaneousness noun

Medical Definition

spontaneous

adjective

spon·​ta·​ne·​ous spän-ˈtā-nē-əs 

1

: proceeding from natural feeling or native tendency without external constraint

2

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

a spontaneous nosebleed

spontaneously adverb