Word
fission
Phoneticsfis·sion, stress on the first syllable
US/ˈfɪʃən/
UK/fˈɪʃən/
Definitions
01nuclear physics
C1 · Advanced Uncountable noun Science Technical
n. the splitting of an atom's center to release a large amount of energy.
n. the process in which the nucleus of a heavy atom splits into two or more smaller nuclei, releasing significant energy.
“Nuclear power plants use fission to create the heat needed for electricity.”
“The discovery of nuclear fission in the late 1930s fundamentally altered the landscape of both global energy production and modern warfare.”
Usage
Often used as a modifier in the phrase 'nuclear fission'.
Synonyms
Antonyms
02biology
C2 · Proficiency Uncountable noun Science Technical
n. a way that some tiny living things, like bacteria, reproduce by splitting in two.
n. a form of asexual reproduction in single-celled organisms where the parent cell divides into two or more daughter cells.
“Bacteria reproduce quickly through a process called binary fission.”
“During binary fission, the genetic material is replicated before the cell membrane pinches inward to create two genetically identical organisms.”
Usage
Commonly appears in the specific biological term 'binary fission'.
Synonyms
03to split apart
C2 · Proficiency Science Technical
v. to split into two or more parts, or to cause something to split.
v. to undergo or cause to undergo the process of splitting into parts.
“The heavy atoms began to fission when they were hit by neutrons.”
“Under specific laboratory conditions, the researchers observed the isotopes as they began to fission at an accelerated rate.”
Usage
Used both transitively and intransitively in scientific contexts.
Antonyms
Real-World Examples
“Generating electricity from the heat unleashed by fissioning uranium atoms is a multistep process, and at each step the composition of the nuclear fuel must be reassessed before proceeding.” “Long-lived radioactive fission products keep decaying for months or even years, releasing a weak stream of particles called antineutrinos.” Etymology
Borrowed from Latin fissiōnem, accusative singular of fissiō (“the act of breaking up”), from findō (“split, divide”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Domain
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.C2 ProficiencyIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.8.5–9.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 6.0114–120
- Frequency
- Occasional
- Level
- C2 · Proficiency
- Updated
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