fallout

American  

[fawl-out] / ˈfɔlˌaʊt /

Or fall-out

noun

1. the settling to the ground of airborne particles ejected into the atmosphere from the earth by explosions, eruptions, forest fires, etc., especially such settling from nuclear explosions radioactive fallout.

2. the particles themselves.

3. an unexpected or incidental effect, outcome, or product.

   the psychological fallout of being obese.

4. effects; results.

   emotional fallout from a divorce.

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fallout British  

/ ˈfɔːlˌaʊt /

noun

1. the descent of solid material in the atmosphere onto the earth, esp of radioactive material following a nuclear explosion

2. any solid particles that so descend

3. informal side-effects; secondary consequences

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verb

1. informal to quarrel or disagree

2. (intr) to happen or occur

3. military to leave a parade or disciplinary formation

1. military the order to leave a parade or disciplinary formation

Etymology

Origin of fallout

First recorded in 1945–50; noun use of verb phrase fall out

Explanation

Fallout is the cloud of radioactive material that falls from the sky after a nuclear blast. Fear of the effects of fallout is just one reason some people are nervous about nuclear energy. Nuclear fallout settles on the ground and in the atmosphere after a nuclear bomb explodes or a reaction occurs at a damaged nuclear power plant. The dangers of this kind of fallout are enormous, including immediate death and long-term illness caused by breathing and eating the radioactive dust. Another kind of fallout is more figurative — it's any kind of negative effect or result, like the fallout from telling your family you're getting an enormous tattoo.

Example Sentences

The rebuke underscores tensions within the administration as it grapples with the economic fallout from the conflict, which has rattled global energy markets.

From Barron's • Apr. 21, 2026

The inflation report offers central bankers a first look at the early fallout from the Iran war ahead of the coming policy decision late this month.

From The Wall Street Journal • Apr. 20, 2026

That’s as continued outperformance of rest-of-the-world stocks versus the U.S. are also hitting speed bumps, due to spiking commodity prices and global growth fallout.

From MarketWatch • Apr. 14, 2026

Brad Conger, chief investment officer at Hirtle Callaghan, said that the fact that the U.S. is a net energy exporter has likely helped insulate stocks from some of the fallout.

From MarketWatch • Apr. 13, 2026

Somewhere, very far off, is a place called District 12, where my mother and sister and friends will have to deal with the fallout from this night.

From "Catching Fire" by Suzanne Collins