Spon-tā'ne-oŭs, a.
a. [Lat. spontaneus, from sponte, of free will, voluntarily; It. spontaneo, Sp. espontaneo, Fr. spontané.]
Sense 1. Proceeding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without compulsion or constraint; as, a spontaneous gift or proposition.
Sense 2. Proceeding from internal impulse, energy, or natural law, without external force; as, spontaneous motion; spontaneous growth.
Sense 3. Produced without being planted, or without human labor; as, a spontaneous growth of wood.
Spontaneous combustion of a substance, a taking fire of itself, by the evolution of heat through the chemical action of its own elements.
Synonyms—Voluntary; uncompelled; willing.—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 by a kind of outburst of the mind which admits of no reflection; as, a spontaneous burst of applause. Hence, the term is sometimes applied to things inanimate. “Abstinence is but voluntary fasting, and exercise but voluntary labor.” Seed. “In man, love is less spontaneous and disinterested than in woman.” Arnold.
Spontaneous joys, where nature has its play, The soul adopts, and owns their first-born sway. Goldsmith.