Pronunciation: (fish'un), [key]
1. the act of cleaving or splitting into parts.
2. Also called nuclear fission. Physics.the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy. Cf. fusion (def. 4).
3. Biol.the division of an organism into new organisms as a process of reproduction.
Physics.to undergo fission.
Physics.to cause to undergo fission.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.