Fission

n.	1.	A cleaving, splitting, or breaking up into parts.
	2.	(Biol.) A method of asexual reproduction among the lowest (unicellular) organisms by means of a process of self-division, consisting of gradual division or cleavage of the into two parts, each of which then becomes a separate and independent organisms; as when a cell in an animal or plant, or its germ, undergoes a spontaneous division, and the parts again subdivide. See Segmentation, and Cell division, under Division.
	3.	(Zool.) A process by which certain coral polyps, echinoderms, annelids, etc., spontaneously subdivide, each individual thus forming two or more new ones. See Strobilation.
	4.	(Physics) The act or process of disintegration of an atomic nucleus into two or more smaller pieces; called also nuclear fission. The process may be spontaneous or induced by capture of neutrons or other smaller nuclei, and usually proceeds with evolution of energy.

Noun	1.	fission - a nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy Synonyms: nuclear fission
	2.	fission - reproduction of some unicellular organisms by division of the cell into two more or less equal parts

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