fission

Word family

• fissile
  adjectiveC1
• fissionable
  adjectiveC1

Synonym discussion

Sense: noun/1

Fission refers specifically to the splitting of an atomic nucleus into roughly equal parts, releasing enormous energy. 'Splitting' is the most general term and can describe anything from a log to an atom — it lacks the precision of 'fission'. 'Disintegration' suggests something breaking into many small pieces or falling apart completely, whereas fission produces two main fragments (plus a few neutrons). 'Fragmentation' implies random breakage into several pieces, not the controlled, energy-releasing split of a nucleus. 'Nuclear reaction' is the broader category: fission is one type of nuclear reaction; fusion and radioactive decay are others. For example, scientists say 'the uranium nucleus underwent fission', not 'the uranium nucleus disintegrated' — the latter would imply it fell apart uselessly rather than releasing usable energy.

Common collocations

Etymology

From Latin 'fissio', meaning 'a splitting or cleaving', which came from the verb 'findere' (to split). The term was first used in biology in the 19th century to describe cell division. In 1938, physicists Lise Meitner and Otto Frisch borrowed the same word to describe the splitting of the atomic nucleus, because the two processes — biological and nuclear — both involve one body dividing into two.