n. 裂开, 分裂, 分体

[化] 裂变

[医] 分裂的; 裂殖的; 核裂变

Fission \Fis"sion\, n. [L. fissio. See {Fissure}.]
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. (Zo["o]l.) 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.
[PJC]