spontaneous

I

(New American Roget's College Thesaurus)

adj. instinctive, automatic, involuntary; extemporaneous, uninhibited, unforced, natural. See impulse, will, freedom.

II

(Roget's IV) modif.

Syn. involuntary, instinctive, unbidden, unplanned, impromptu, ad-lib*, casual, unintentional, impulsive, offhand, automatic, unforced, natural, inevitable, irresistible, unavoidable, resistless, unwilling, unconscious, uncontrollable.

Ant. deliberate*, willful, intended.

Syn.- 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 ]

III

(Roget's 3 Superthesaurus) a.

unrehearsed, off the cuff, extemporaneous, unprepared, spur of the moment, unplanned, impulsive, impromptu, *off the top of one's head, ad-lib, unpremeditated, reflexive, natural, instinctual.

ANT.: planned, premeditated, rehearsed, prepared, unnatural

IV

(Roget's Thesaurus II) adjective 1. Acting or happening without apparent forethought, prompting, or planning: automatic, impulsive, instinctive, involuntary, reflex, unpremeditated. See PLANNED. 2. Done by one's own choice: free, uncompelled, unforced, volitional, voluntary, willful. See WILLING. 3. Unconstrained by rigid standards or ceremony: casual, easy, easygoing, informal, natural, relaxed, unceremonious, unrestrained. Informal: laid-back. See PLAIN, TIGHTEN.