Spontaneous vs. Extemporaneous

Spontaneousadjective

Self-generated; happening without any apparent external cause.

‘He made a spontaneous offer of help.’;

Extemporaneousadjective

Without preparation or advanced thought; offhand.

‘"The lovely words of a prepared speech however cannot erase extemporaneous words and deeds — thousands of them — that have run contrary to those aspirations.”’;

Spontaneousadjective

Done by one's own free choice, or without planning.

Extemporaneousadjective

Composed, performed, or uttered on the spur of the moment, or without previous study; unpremeditated; off-hand; ad-lib; extempore; extemporary; as, an extemporaneous address or production.

Spontaneousadjective

Proceeding from natural feeling or native tendency without external or conscious constraint

Extemporaneousadjective

with little or no preparation or forethought;

‘his ad-lib comments showed poor judgment’; ‘an extemporaneous piano recital’; ‘an extemporary lecture’; ‘an extempore skit’; ‘an impromptu speech’; ‘offhand excuses’; ‘trying to sound offhanded and reassuring’; ‘an off-the-cuff toast’; ‘a few unrehearsed comments’;

Spontaneousadjective

Arising from a momentary impulse

Spontaneousadjective

Controlled and directed internally; self-active; spontaneous movement characteristic of living things

Spontaneousadjective

Produced without being planted or without human labor; indigenous

‘a spontaneous growth of wood’;

Spontaneousadjective

Random.

Spontaneousadjective

Sudden, without warning.

Spontaneousadjective

Proceeding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a spontaneous gift or proposition.

Spontaneousadjective

Proceeding from, or acting by, internal impulse, energy, or natural law, without external force; as, spontaneous motion; spontaneous growth.

Spontaneousadjective

Produced without being planted, or without human labor; as, a spontaneous growth of wood.

‘Spontaneous joys, where nature has its play,The soul adopts, and owns their firstborn away.’;

Spontaneousadjective

happening or arising without apparent external cause;

‘spontaneous laughter’; ‘spontaneous combustion’; ‘a spontaneous abortion’;

Spontaneousadjective

said or done without having been planned or written in advance;

‘he made a few ad-lib remarks’;

Spontaneousadjective

produced without being planted or without human labor;

‘wild strawberries’;