Fis'sion, n.

(fish'un), n. [Lat. fissio. See supra.]

1. A cleaving, splitting, or breaking up into parts.
2. (Physiol.) A subdividing into two parts from the progress of natural growth, as when a cell in an animal or plant, or its germ, undergoes a spontaneous division, and the parts again subdivide; so also when an animalcule or polyp divides in an analogous manner into two parts. Dana.