critical mass
Americannoun
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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.
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an amount necessary or sufficient to have a significant effect or to achieve a result.
a critical mass of popular support.
noun
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the minimum mass of fissionable material that can sustain a nuclear chain reaction
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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
Etymology
Origin of critical mass
First recorded in 1940–45
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
What happens next depends on whether this thing achieves a critical mass of meme status.
From Barron's • Apr. 16, 2026
"And therefore, because there's no critical mass, they are really not part of the core of this small start-up village. And therefore, in my opinion we need to create critical mass."
From BBC • Dec. 7, 2025
With such fragmentation, it’s much harder for a negative storyline to reach critical mass.
From Los Angeles Times • Nov. 30, 2025
And male monopolies on power tend to be self-perpetuating: Only when a critical mass of women run and win does it begin to feel possible that women can run for office and win.
From Slate • Nov. 22, 2025
A critical mass would not be achieved, and the bomb would fizzle.
From "Bomb" by Steve Sheinkin
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
