chain reaction

American  

noun

• chain reactions
  plural

1. Physics. a self-sustaining reaction in which the fission of nuclei of one generation of nuclei produces particles that cause the fission of at least an equal number of nuclei of the succeeding generation.

2. Chemistry. a reaction that results in a product necessary for the continuance of the reaction.

3. a series of events in which each event is the result of the one preceding and the cause of the one following.

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chain reaction British  

noun

1. a process in which a neutron colliding with an atomic nucleus causes fission and the ejection of one or more other neutrons, which induce other nuclei to split

2. a chemical reaction in which the product of one step is a reactant in the following step

3. a series of rapidly occurring events, each of which precipitates the next

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chain reaction Scientific  

1. A process in which the result of one event triggers another event, usually of the same kind, which in turn triggers yet another event, so that the overall reaction tends to be self-sustaining. Nuclear fission reactions are chain reactions, in which the splitting of an atomic nucleus releases neutrons that penetrate other nuclei, causing them to split. The spread of heat through a substance is also a chain reaction, as fast-moving molecules in a hot part of the substance collide with neighboring molecules, passing on their kinetic energy to them, thereby making more of the substance warmer.

2. See more at fission See Note at nuclear reactor See also kinetic theory

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chain reaction Cultural  

1. In chemistry and physics, a self-sustaining series of reactions. In a chain reaction in a uranium-based nuclear reactor, for example, a single neutron causes the nucleus of a uranium atom to undergo fission. In the process, two or three more neutrons are released. These neutrons start more fissions, which produce more neutrons, and so on.

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chain reaction Idioms  

1. A series of events in which each influences or gives rise to the next event, as in If one person collects substantial damages by suing a company, you can expect a chain reaction of such lawsuits. The term originated in the physical sciences, first (1920s) chemistry and later (1940) physics; in the latter it denotes a process of nuclear fission. By the 1940s it had been transferred to more general use.

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Discover More

Figuratively speaking, any group of events linked so that one is the cause of the next can be called a “chain reaction.”

Other Word Forms

Noun Inflected Forms

• chain reactions
  plural

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Etymology

Origin of chain reaction

First recorded in 1925–30

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Example Sentences

See Examples For:

chain reaction

Slower neutrons are more likely to trigger additional fission reactions in uranium, helping sustain the chain reaction needed for a working reactor.

From Science Daily ● Oct. 16, 2026

Even a small liquidation in such a tightly coupled system can produce a chain reaction with major consequences.

From MarketWatch ● Sep. 23, 2026

One possibility is that water from rainfall or melting ice may have destabilised the ground or ice, triggering a chain reaction.

From BBC ● Aug. 26, 2026

When the Thai stock market collapse later that year, it started a chain reaction that cost him his hedge fund, a significant portion of his substantial personal wealth, and his reputation.

From The Wall Street Journal ● Aug. 21, 2026

It all sounds easy enough, but in practice, starting that chain reaction is an extremely tricky process.

From "Meltdown" by Deirdre Langeland

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Related Words

• chemical reaction
• vicious circle

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