critical mass

[ krit-i-kuhl mas ]
See synonyms for critical mass on Thesaurus.com
noun
  1. Physics. the amount of a given fissionable material necessary to sustain a chain reaction at a constant rate: The critical mass for a bomb based on uranium fission is different than that for plutonium fission.

  2. an amount necessary or sufficient to have a significant effect or to achieve a result: a critical mass of popular support.

Origin of critical mass

1
First recorded in 1940–45

Words Nearby critical mass

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use critical mass in a sentence

British Dictionary definitions for critical mass

critical mass

noun
  1. the minimum mass of fissionable material that can sustain a nuclear chain reaction

  2. the minimum amount of money or number of people required to start or sustain an operation, business, process, etc: the critical mass for a subscription digital sports channel

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for critical mass

critical mass

  1. The smallest mass of a fissionable material that will sustain a nuclear chain reaction.

  2. The amount of matter needed to generate sufficient gravitational force to halt the current expansion of the universe. See also big bang big crunch.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for critical mass

critical mass

In physics, the amount of material that must be present before a chain reaction can sustain itself.

Notes for critical mass

The term critical mass is used to refer generally to the minimum amount of something needed to produce a given effect: “The town needs a critical mass of industry to attract more business.”

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.