chain reaction

noun

1

a

: a series of events so related to each other that each one initiates the next

b

: a number of events triggered by the same initial event

2

: a self-sustaining chemical or nuclear reaction yielding energy or products that cause further reactions of the same kind

chain-react

ˈchān-rē-ˈakt 

intransitive verb

Examples of chain reaction in a Sentence

Increased oil prices could trigger a chain reaction in the economy.

Recent Examples on the Web

Video shared on social media shows the chain reaction crash in which one police all-terrain vehicle rear-ends another, pushing it into at least two pedestrians and then hitting a boardwalk tram car. — Laura Fay, CBS News, 12 July 2026

In medicine, this is often called a diagnostic cascade, a chain reaction of additional tests triggered by an uncertain finding. — Felicity Yost, Forbes.com, 10 July 2026

Standard nuclear reactors rely on a self-sustaining chain reaction. — Aman Tripathi, Interesting Engineering, 8 July 2026

Twelve years after this, nuclear physicist Hans Bethe formulated the first explanation of this nuclear fusion process, detailing the proton-proton chain reaction and the Carbon-Nitrogen-Oxygen (CNO) cycle. — Robert Lea, Space.com, 3 July 2026

Word History

First Known Use

1892, in the meaning defined at sense 1a

Rhymes for chain reaction

• abstraction
• attraction
• compaction
• contraction
• detraction
• diffraction
• distraction
• exaction
• extraction
• impaction
• inaction
• infraction

Kids Definition

chain reaction

noun

1

: a series of events so related to each other that each one sets the next one going

2

: a chemical or nuclear reaction producing energy or products that cause further reactions of the same kind

Medical Definition

chain reaction

noun

: a self-sustaining chemical or nuclear reaction yielding energy or products that cause further reactions of the same kind