fallout

American  

[fawl-out] / ˈfɔlˌaʊt /

Or fall-out

noun

fallouts plural

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

Other Word Forms

Noun Inflected Forms

• fallouts
  plural

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

Fallout from the Iran war, as well as soaring labor costs, are driving more businesses to reduce recruitment and limit pay hikes, he added.

From The Wall Street Journal • May 19, 2026

Since “Queer Roast’s” start at the Pack, shows have ventured to the Elysian Theater, Fallout Theater in Austin, Texas, and are slowly making a home at Beaches Tropicana.

From Los Angeles Times • May 18, 2026

Fallout from that arrangement could help foster a stronger relationship between AMD and OpenAI, Luria said.

From MarketWatch • May 8, 2026

In recent years, Christopher Nolan’s Oppenheimer, the journalist Annie Jacobsen’s bestselling Nuclear War: A Scenario, and the video game–turned–TV show Fallout have tackled hypothetical armageddon.

From Slate • Mar. 13, 2026

Fallout from the meltdowns will affect the region for decades, possibly centuries.

From "Meltdown" by Deirdre Langeland