fission

[ fish-uhn ]

noun

1. the act of cleaving or splitting into parts.
2. Also called nu·cle·ar fis·sion [noo, -klee-er , fish, -, uh, n, nyoo, -]. Physics. the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy. Compare fusion ( def 4 ).
3. Biology. the division of an organism into new organisms as a process of reproduction.

verb (used without object)

1. Physics. to undergo fission.

verb (used with object)

1. Physics. to cause to undergo fission.

fission

/ ˈfɪʃən /

noun

1. the act or process of splitting or breaking into parts
2. biology a form of asexual reproduction in single-celled animals and plants involving a division into two or more equal parts that develop into new cells
3. short for nuclear fission

fission

/ fĭsh′ən /

1. The splitting of an unstable atomic nucleus into two or more nuclei. Fission occurs spontaneously, generally when a nucleus has an excess of neutrons, resulting in the inability of the strong force to bind the protons and neutrons together. The fission reaction used in many nuclear reactors and bombs involves the absorption of neutrons by uranium-235 nuclei, which immediately undergo fission, releasing energy and fast neutrons .
2. Compare fusion
3. A process of asexual reproduction in which a single cell splits to form two identical, independent cells. In fission, the chromosomal DNA replicates before the cell divides. Most bacteria and other prokaryotes reproduce by means of fission.
4. Also called binary fission

Word History and Origins

Origin of fission¹

First recorded in 1835–45; from Latin fissiōn- (stem of fissiō ) “a splitting, dividing,” equivalent to fiss(us) “divided” + -iōn- noun-forming suffix; fissi-, -ion; fission def 2 was first recorded in 1935–40

Word History and Origins

Origin of fission¹

C19: from Latin fissiō a cleaving

Example Sentences

The reaction creates helium and not the long-lived radioactive waste of the fission process which is used in existing nuclear power stations.

From BBC

Today, the plant is still buzzing with life: Nuclear fission, in the deep heart of the plant, continues to superheat water to 600 degrees at 150 times atmospheric pressure.

From Los Angeles Times

With calculations based on linear algebra, the research team demonstrated that -- analogous to radioactivity in atomic nuclei -- a magnetic quiver can decay into a more stable state or fission into two separate quivers.

From Science Daily

Utsunomiya continued, "because we knew that most of the Cs in CsMPs is fission derived, we thought that analysis of the pollucite could yield the first ever direct images of radioactive Cs atoms."

From Science Daily

Using a mechanism called paratomic fission, the worm starts forming and differentiating new head and tail segments from within a single body segment, producing what is known as a "chain of worms."

From Science Daily