fall·​out | \ˈfȯl-ˌau̇t \

Definition of fallout 

(Entry 1 of 2)

1a : 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


Definition of fall out (Entry 2 of 2)

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

3a : to leave one's place in the ranks

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

Keep scrolling for more

Examples of fallout in a Sentence


concerned about the possible political fallout from the scandal


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.
See More

Recent Examples on the Web: Noun

The scientists’ claim has mostly centered on discoveries of purported impact fallout material at archeological sites in the North America. Scott K. Johnson, Ars Technica, "Huge, previously unknown impact crater found beneath Greenland’s ice," 18 Nov. 2018 Bansal’s ouster comes months after his fellow Flipkart founder, Sachin Bansal (no relation), was forced out of the company during its sale talks with Walmart in April, following a bitter fallout with the then-board of Flipkart. Recode Staff, Recode, "Recode Daily: Waymo is launching the world’s first driverless car service next month," 14 Nov. 2018 Taser rounds would give grunts the ability to take down individuals who present less than a lethal threat and avoid nasty diplomatic fallout from lethal shootings. Kyle Mizokami, Popular Mechanics, "The Marines Want Non-Lethal Taser Rounds to Stun Angry Crowds," 6 Sep. 2018 Celebrities, including Caitlyn Jenner and her son-in-law, Kanye West, have faced heavy criticism and fallout from fans for wearing the hat. Amira Rasool, Teen Vogue, "Student Arrested on Battery Charges After Removing MAGA Hat From Classmate's Head," 29 Aug. 2018 Seattle isn’t the only city that’s currently grappling with air quality issues: People from Oregon to Colorado are facing the air quality fallout from wildfires, according to the Associated Press. Korin Miller, SELF, "How to Stay Safe When Your City’s Air Quality Is Dangerous," 21 Aug. 2018 The longer ones of the Triad Concealer Brush, on the other hand, often cause fallout. Devon Abelman, Allure, "How I Inspired Moda's Triad Eye Brush, the Only Tool I Need for a Complete Shadow Look," 16 Aug. 2018 In a new interview with the Daily Mail, Thomas, 74, has decided to address those staged paparazzi photos and the resulting fallout his faced with the royal family. Kayleigh Roberts, Marie Claire, "Thomas Markle Reportedly Lied to and Hung Up on Prince Harry During a Call About Those Staged Pictures," 12 Aug. 2018 Her tenure was immediately consumed by the fallout from Fowler's allegations, revamping the ride-sharing giant's culture and implementing the 47 recommendations made by former Atty. Hamza Shaban And Jena Mcgregor, latimes.com, "Uber's HR chief resigns, reportedly after discrimination investigation," 11 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fallout.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of fallout


1946, in the meaning defined at sense 1a


15th century, in the meaning defined at sense 1

Keep scrolling for more

Learn More about fallout

Statistics for fallout

Last Updated

6 Dec 2018

Look-up Popularity

Time Traveler for fallout

The first known use of fallout was in the 15th century

See more words from the same century

Keep scrolling for more

More Definitions for fallout



English Language Learners Definition of fallout

: the radioactive particles that are produced by a nuclear explosion and that fall through the atmosphere

: a bad effect or result of something


fall·​out | \ˈfȯl-ˌau̇t \

Kids Definition of fallout

1 : the usually radioactive particles falling through the atmosphere as a result of a nuclear explosion

2 : the bad result of something He suffered the fallout from his poor decision.


fall·​out | \ˈfȯ-ˌlau̇t \

Medical Definition of fallout 

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

Keep scrolling for more

More from Merriam-Webster on fallout

Rhyming Dictionary: Words that rhyme with fallout

Spanish Central: Translation of fallout

Nglish: Translation of fallout for Spanish Speakers

Britannica English: Translation of fallout for Arabic Speakers

Britannica.com: Encyclopedia article about fallout

Comments on fallout

What made you want to look up fallout? Please tell us where you read or heard it (including the quote, if possible).


a knickknack or trinket

Get Word of the Day daily email!

Test Your Vocabulary

Find the Cousins

  • a-large-tree-with-many-branches
  • Which pair shares a common word ancestor?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Word Winder's CrossWinder

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!