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

I 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 of fallout

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

Neither set of negotiations is showing much progress, but Rubio has escaped the fallout. — Max Boot, Washington Post, 27 July 2026

Nvidia and a host of tech giants on Monday launched a new artificial intelligence safety initiative focused on open models, as the fallout from a cyberattack committed by rogue OpenAI models continues. — Kai Nicol-Schwarz, CNBC, 27 July 2026

Verb

With the lead down to five, the K-State standout hit a long 2 while falling out of bounds in the left corner. — Christian Marshall, Kansas City Star, 23 July 2026

The employee fell out of the moving train's door and was injured. — ABC News, 21 July 2026

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