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 Bank of Japan is expected to raise interest rates on June 16 as policymakers grow more concerned that the fallout from the conflict will accelerate underlying inflation.

From The Wall Street Journal • Jun. 8, 2026

She estimated that vulnerable economies would need between $20-50 billion in financial assistance due to the economic fallout of the conflict.

From Barron's • Jun. 4, 2026

Amid uncertainty in the toy market and the fallout from tariffs, Mattel’s net income dropped 25% to $398 million in 2025.

From Los Angeles Times • Jun. 4, 2026

The prime minister has a long history of testing the White House's patience - and of politically surviving any fallout.

From BBC • Jun. 3, 2026

Not only the target insect or plant, but anything — human or nonhuman — within range of the chemical fallout may know the sinister touch of the poison.

From "Silent Spring" by Rachel Carson