fallout

1 of 2

noun

fall·​out ˈfȯl-ˌau̇t 

1

a

: the often radioactive particles stirred up by or resulting from a nuclear explosion and descending through the atmosphere

also : other polluting particles (such as volcanic ash) descending likewise

b

: descent (as of fallout) through the atmosphere

2

: a secondary and often lingering effect, result, or set of consequences

have to take a position and accept the political fallout

—Andy Logan

fall out

2 of 2

verb

fell out; fallen out; falling out; falls out

intransitive verb

1

: quarrel

also : to cut off relations over a quarrel

former friends who have fallen out

2

: turn out, happen

expected to be in the States …  , but things fell out otherwise

—Mark Twain

3

a

: to leave one's place in the ranks

b

: to leave a building in order to take one's place in a military formation

Synonyms

Verb

• bicker
• fight
• argue
• spat
• quarrel
• clash

Examples of fallout in a Sentence

Noun

concerned about the possible political fallout from the scandal

Verb

club members were soon falling out about how to spend the money they'd made washing cars

I had planned to have a sports career, but things fell out otherwise.

Recent Examples on the Web

Noun

Fortnite could have tested for misuse and emotional risk of its AI voice feature, protecting its brand from reputational fallout. —Toby Wong, Forbes.com, 1 July 2025

In true underworld fashion, García tried to shield himself from the fallout. —Gina Montaner, Miami Herald, 1 July 2025

Verb

So when both astronomers and the operators of the clocks notice that the atomic ticks are falling out of step with the rotation of the Earth, people take notice. —Jeffrey Kluger, Time, 9 July 2025

This mini travel jewelry case has separate compartments for your rings, earrings, and necklaces, and fully zips, preventing any pieces from falling out. —Amelia McBride, Travel + Leisure, 9 July 2025

Word History

First Known Use

Noun

1946, in the meaning defined at sense 1a

Verb

15th century, in the meaning defined at sense 1

Phrases Containing fallout

• fallout shelter

Rhymes for fallout

• about
• bailout
• blackout
• blowout
• breakout
• burnout
• buyout
• checkout
• closeout
• cutout
• devout
• dropout

Kids Definition

fallout

1 of 2 noun

fall·​out ˈfȯ-ˌlau̇t 

: the often radioactive particles that are stirred up by or result from a nuclear explosion and descend through the atmosphere

fall out

2 of 2 verb

(ˈ)fȯ-ˈlau̇t

1

: to have a quarrel

2

: happen sense 1

Medical Definition

fallout

noun

fall·​out ˈfȯ-ˌlau̇t 

1

: the often radioactive particles stirred up by or resulting from a nuclear explosion and descending through the atmosphere

also : other polluting particles (as volcanic ash) descending likewise

2

: descent (as of fallout) through the atmosphere