3. Produced without being planted, or without human labour; as, a spontaneous growth of wood. Spontaneous combustion, combustion produced in a substance by the evolution of heat through the chemical action of its own elements; as, the spontaneous combustion of waste matter saturated with oil. Spontaneous generation.
(Science: biology) See generation.
Spontaneous, voluntary. What is voluntary is the result of a volition, or act of choice; it therefore implies some degree of consideration, and may be the result of mere reason without excited feeling. What is spontaneous springs wholly from feeling, or a sudden impulse which admits of no reflection; as, a spontaneous burst of applause. Hence, the term is also applied to things inanimate when they are produced without the determinate purpose or care of man. Abstinence which is but voluntary [[fa 576 sting]], and . . . Exercise which is but voluntary labour. Spontaneous joys, where nature has its play, The soul adopts, and owns their firstborn away. (goldsmith) Spontaneously, Spontaneousness.
Origin: L. Spontaneus, fr. Sponte of free will, voluntarily.