Definition of spontaneous
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
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Merriam-Webster unabridgedWords at Play
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Time Traveler for spontaneous
The first known use of spontaneous was in 1605
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