weak force


Definition of weak force

: a fundamental physical force that governs interactions between hadrons and leptons (as in the emission and absorption of neutrinos) and is responsible for particle decay processes (such as beta decay) in radioactivity, that is 10-5 times the strength of the strong force, and that acts over distances smaller than those between nucleons in an atomic nucleus

called also weak interaction, weak nuclear force

— compare electromagnetism sense 2a, gravity sense 3a(2), strong force

Examples of weak force in a Sentence

Recent Examples on the Web

Neutrinos eschew the strong and electromagnetic forces, maintaining only the most tenuous of ties to the rest of the universe through the weak force and gravity. Quanta Magazine, "On a Hunt for a Ghost of a Particle," 8 Dec. 2016 In this scenario, a WIMP would tap an atomic nucleus via the weak force. Quanta Magazine, "Why the Best Place to Find Dark Matter May Be in a Rock," 7 Jan. 2019 What will govern the economy if mass consumption becomes a weaker force? Marilynne Robinson, Harper's magazine, "Is Poverty Necessary?," 10 June 2019 To the east, the Soviet Union is a much weaker force and still Germany’s ally. Bartle Bull, WSJ, "‘Blood, Oil and the Axis’ Review: The Front That Was Left Behind," 9 May 2019 The scientists focused on the weak interaction, also known both as the weak force and the weak nuclear force. Charles Q. Choi, Space.com, "Why Alternate Universes Might Also Host Life Around their Stars," 26 Sep. 2018 In universes with a weaker weak force, neutrons would decay more slowly, leading to more helium. Charles Q. Choi, Space.com, "Why Alternate Universes Might Also Host Life Around their Stars," 26 Sep. 2018 Previous research found that a universe where the weak force is entirely absent could still be habitable. Charles Q. Choi, Space.com, "Why Alternate Universes Might Also Host Life Around their Stars," 26 Sep. 2018 But some researchers have proposed a type of neutrino that doesn't interact via the weak force, leaving its only interactions to come via gravity. John Timmer, Ars Technica, "Weird neutrino excess won’t go away, hints at new physics," 8 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'weak force.' 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 weak force

1968, in the meaning defined above

Keep scrolling for more

Learn More about weak force

Statistics for weak force

Last Updated

17 Jul 2019

Look-up Popularity

Time Traveler for weak force

The first known use of weak force was in 1968

See more words from the same year

More from Merriam-Webster on weak force

Britannica.com: Encyclopedia article about weak force

Comments on weak force

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


to complain fretfully

Get Word of the Day daily email!

Test Your Vocabulary

What's that Smell?! Quiz

  • wide eyed dog smelling rose
  • Someone who is hircine smells like a:
Name That Thing

Test your visual vocabulary with our 10-question challenge!


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!