Physics. the amount of a given fissionable material necessary to sustain a chain reaction at a constant rate.
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
First recorded in 1940–45
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
the minimum mass of fissionable material that can sustain a nuclear chain reaction
the minimum amount of money or number of people required to start or sustain an operation, business, process, etcthe 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
The smallest mass of a fissionable material that will sustain a nuclear chain reaction.
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.
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.