# fission

/ˈfɪʃən/ (US) · /fˈɪʃən/ (UK)

Source: https://englishreference.com/word/fission
Updated: 2026-08-27

## Senses

### 1. nuclear physics

noun · CEFR C1 · Technical

the splitting of an atom's center to release a large amount of energy.

For teachers: 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'.

### 2. biology

noun · CEFR C2 · Technical

a way that some tiny living things, like bacteria, reproduce by splitting in two.

For teachers: 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'.

### 3. to split apart

verb · CEFR C2 · Technical

to split into two or more parts, or to cause something to split.

For teachers: 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.

## Examples

- Bacteria reproduce through a process called binary fission.
- During binary fission, the single-celled organism duplicates its genetic material and then divides into two identical parts.
- While nuclear fission involves splitting heavy atomic nuclei to release energy, biological fission serves as a primary mechanism for population growth in prokaryotic organisms.

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