Performed or occurring as a result of a sudden inner impulse or inclination and without premeditation or external stimulus. Her spontaneous laughter filled the room with joy.
Natural and unconstrained; unplanned. The spontaneous growth of wildflowers added beauty to the meadow.
Occurring without apparent external cause; self-generated, especially in scientific or medical contexts. Spontaneous emission of light occurs when an excited electron drops to a lower energy level.