Spontaneous Definition

spŏn-tānē-əs

adjective

Having no apparent external cause or influence; occurring or produced by its own energy, force, etc. or through internal causes; self-acting.

Webster's New World

Acting in accordance with or resulting from a natural feeling, impulse, or tendency, without any constraint, effort, or premeditation.

Webster's New World

Unconstrained and unstudied in manner or behavior.

A spontaneous personality.

American Heritage

Growing naturally without being planted or tended; indigenous; wild.

Webster's New World

Done by one's own free choice, or without planning.

Wiktionary

Synonyms:

Antonyms:

Origin of Spontaneous

From Late Latin spontāneus of one's own accord from Latin sponte (s)pen- in Indo-European roots

From American Heritage Dictionary of the English Language, 5th Edition
Late Latin spontaneus, from Latin sponte (sua) (“of one's free will, voluntarily").

From Wiktionary