fis|sion

fis|sion «FIHSH uhn», noun, verb.

–n.

1. the splitting of atoms which releases tremendous amounts of energy and is used to start the chain reaction of an atomic explosion; nuclear fission. It occurs when the nucleus of an atom is bombarded by neutrons, absorbs a neutron, and then divides into two nearly equal parts. »

Atomic power plants and nuclear submarines are powered by the energy of fission (Ralph E. Lapp).

2. a method of reproduction in which the body of the parent divides to form two or more independent individuals. Many simple plants and animals reproduce by fission.

3. a splitting apart; division into parts: »

The appearance in Kenya of tendencies to political fission along tribal lines was of greater concern than similar developments in…other countries (Arthur C. Turner).

–v.t., v.i.

to split or divide: »

Although it will not fission, U-238 can absorb a neutron to become U-239, an unstable element which decays in several days to a new element, plutonium (Science News). The McCarthy “new politics movement…fissioned the state party, the Democratic-Farmer Labor Party (Austin C. Wehrwein).

╂[< Latin fissiō, -ōnis < findere cleave]