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

But Oceanwide is grappling with the fallout from a deadly hantavirus outbreak on a recent voyage that included stops to remote islands in the South Atlantic Ocean.

From The Wall Street Journal • May 17, 2026

KFC CEO Scott Mezvinsky said he thinks highlighting the protein in the chain’s chicken and smaller, snack-sized portions can help the fast-food chain navigate fallout from the drugs.

From The Wall Street Journal • May 13, 2026

Danish wind power giants Vestas and Orsted have also reported surging profits, highlighting how the fallout from the Iran war is also boosting renewable energy firms.

From BBC • May 8, 2026

Now, as health officials and the travel industry cope with the fallout from the cruise outbreak, the lack of attention to hantaviruses appears short-sighted.

From MarketWatch • May 8, 2026

A smile of lath opened amid powdery fallout.

From "Typical American" by Gish Jen