Synonyms for spontaneous

modified

spontaneous applies to that which is done so naturally that it seems to come without prompting or premeditation a spontaneous demonstration; impulsive applies to that which is prompted by some external incitement or sudden inner inclination rather than by conscious rational volition an impulsive retort; instinctive suggests an immediate, unwilled response to a stimulus, as if prompted by some natural, inborn tendency he took an instinctive liking to her; involuntary refers to that which is done without thought or volition, as a reflex action an involuntary scowl, an involuntary flicker of the eyelid; automatic suggests an unvarying, machinelike reaction to a given stimulus or situation an automatic response