Spontaneous

 WORD OF THE DAY

spontaneous / adjective / spahn-TAY-nee-us

Definition
1: proceeding from natural feeling or native tendency without external constraint
2: arising from a momentary impulse
3a: controlled and directed internally
3b: self-acting
4a: produced without being planted or without human labor
4b: indigenous
5: developing or occurring without apparent external influence, force, cause, or treatment
6a: not apparently contrived or manipulated
6b: natural

Examples
"'You're coming to San Diego?' said Courtney excitedly. 'I am. I've decided to be spontaneous for once.' She paused. 'Which means that the visit is on short notice. Sorry about that.'"
— Douglas E. Richards, The Cure, 2013

"The key, Strassman says, is to give employees opportunities to spend unstructured work time together. Such moments can reduce social isolation and increase spontaneous collaboration and creativity—while not adding more meetings to already-full calendars."
— Barbara Z. Larson, Harvard Business Review, 27 Oct. 2020

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.