fission

1 of 2

noun

fis·​sion ˈfi-shᵊn  -zhᵊn 

1

: a splitting or breaking up into parts

2

: reproduction by spontaneous division of the body into two or more parts each of which grows into a complete organism

3

: the splitting of an atomic nucleus resulting in the release of large amounts of energy

fissional

ˈfi-shə-nəl  -zhə- 

adjective

fission

2 of 2

verb

fissioned; fissioning; fissions

intransitive verb

: to undergo fission

transitive verb

: to cause to undergo fission

Examples of fission in a Sentence

Recent Examples on the Web

Noun

The team's approach centers on a phenomenon called singlet fission. — New Atlas, 13 Apr. 2026

Nuclear power takes advantage of the energy released when the nucleus of an atom, such as uranium, splits in a process called fission. — ABC News, 17 Apr. 2026

Verb

Most atoms do not fission, but the isotopes of certain elements, such as uranium-235, are fissile. — Washington Post, 28 Apr. 2022

When a neutron hits a uranium nucleus, that nucleus then fissions into two smaller nuclei while emitting more neutrons. — IEEE Spectrum, 30 July 2010

Word History

Etymology

Noun

borrowed from Latin fissiōn-, fissiō, from fid-, variant stem of findere "to split, cleave" + -tiōn-, -tiō, suffix of verbal action — more at bite entry 1

Verb

derivative of fission entry 1

First Known Use

Noun

circa 1617, in the meaning defined at sense 1

Verb

1929, in the meaning defined at intransitive sense

Phrases Containing fission

• binary fission
• nuclear fission

Rhymes for fission

• dition
• lycian
• abolition
• acquisition
• admonition
• ammunition
• apparition
• apposition
• coalition
• competition
• composition
• definition

Kids Definition

fission

1 of 2 noun

fis·​sion ˈfish-ən 

also ˈfizh-

1

: a splitting or breaking up into parts

2

: a method of reproduction in which a living cell or body divides into two or more parts each of which grows into a whole new individual

3

: the splitting of an atomic nucleus resulting in the release of large amounts of energy

fission

2 of 2 verb

fissioned; fissioning

ˈfish-(ə-)niŋ, 

ˈfizh-

: to go through or cause to go through fission

Medical Definition

fission

noun

fis·​sion ˈfish-ən also ˈfizh- 

1

: a method of reproduction in which a living cell or body divides into two or more parts each of which grows into a whole new individual

2

a

: cleavage sense 2

b

: the splitting of an atomic nucleus resulting in the release of large amounts of energy

called also nuclear fission

fission verb

fissioned; fissioning ˈfish-(ə-)niŋ also ˈfizh- 

fissional

ˈfish-ən-ᵊl also ˈfizh- 

adjective