The quality of being spontaneous and coming from natural feelings without constraint:
— The spontaneity of his laughter.

synonym: spontaneousness.

Roget 600: will, volition, conation^†, velleity; liberum arbitrium [Lat.]; will and pleasure, free will; freedom etc. 748; discretion; option etc. (choice) 609; voluntariness^†; spontaneity, spontaneousness; originality.    pleasure, wish, mind; desire; frame of mind etc. (inclination) 602; intention etc. 620; predetermination etc. 611; selfcontrol &c.; determination etc. (resolution) 604; force of will.    ... show more

Dutch: spontaniteit, spontaneïteit
Polish: spontaniczność