| spontaneous | 1. Proceding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a spontaneous gift or proportion. 2. Proceeding from, or acting by, internal impulse, energy, or natural law, without external force; as, spontaneous motion; spontaneous growth. 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. <biology> See Generation. Synonym: 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, 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 fasting, and . . . Exercise which is but voluntary labour." "Spontaneous joys, where nature has its play, The soul adopts, and owns their firstborn away." (Goldsmith) Sponta"neously, Sponta"neousness. Origin: L. Spontaneus, fr. Sponte of free will, voluntarily. Source: Websters Dictionary (01 Mar 1998) |
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| spontaneous abortion | The sudden unplanned evacuation of the uterus. (27 Sep 1997) |
| spontaneous agglutination | The non-specific clumping of organisms in saline related to lack of polar groups in electrolyte solution. (05 Mar 2000) |
| spontaneous amputation | Amputation as the result of a pathologic process rather than external trauma. (05 Mar 2000) |
| spontaneous breech extraction | Delivery of a foetus in the breech presentation without extraction by the obstetrician. (05 Mar 2000) |
| spontaneous cephalic delivery | Unassisted expulsion of a foetus that presents by the head. (05 Mar 2000) |
| spontaneous combustion | A circumstance where a substance or organism takes fire and burns without an exogenous source. Spontaneous human combustion differs from preternatural human combustibility in that in the latter, some spark or trivial flame sets the fire and the body tissues, which have a greatly enhanced inflammability, continue to undergo incineration without any external heat source or combustible materials. (bergman na. Spontaneous human combustion: its role in literature and science. Pharos 1988;fall;51(4):18-21) (12 Dec 1998) |
| spontaneous correction of placenta previa | The upward "migration" of the placenta away from the internal os by the differential growth rates of upper and lower uterine segments. (05 Mar 2000) |
| spontaneous emission | <radiobiology> Radiation randomly emitted by excited atoms or ions. Contrast with stimulated emission. (09 Oct 1997) |
| spontaneous evolution | The unaided delivery of the foetus from a transverse lie. (05 Mar 2000) |
| spontaneous fracture | A fracture occurring without any external injury. (05 Mar 2000) |
| spontaneous gangrene of newborn | Gangrene due to vascular occlusion of unknown cause, usually in marasmic or dehydrated infants. (05 Mar 2000) |
| spontaneous generation | The obsolete hypothesis that living organisms can originate from nonliving matter. (09 Oct 1997) |
| spontaneous intermittent mandatory ventilation | Intermittent mandatory ventilation spontaneously initiated by the patient, to increase tidal volume, and subsequently synchronised with patient's respiratory cycle. Synonym: synchronised intermittent mandatory ventilation. (05 Mar 2000) |
| spontaneous mutation | A mutation which occurs by itself without first being affected by a mutagen, for example during the process of DNA replication. Spontaneous mutations arise at a remarkably constant rate. The rate that spontaneous mutations arise has been used as an evolutionary clock to estimate how closely related two (or more) separate species are to each other. (09 Oct 1997) |