noun the tendency to activity of muscular tissue, including the voluntary muscles, when in a state of healthful vigor and refreshment.
2. spontaneity ·noun the tendency to undergo change, characteristic of both animal and vegetable organisms, and not restrained or cheked by the environment.
3. spontaneity ·noun the quality or state of being spontaneous, or acting from native feeling, proneness, or temperament, without constraint or external force.