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.
Still, like many EVs, critical mass was hard to achieve.
From The Wall Street Journal ● Jul. 16, 2026
In the 2010s, conversations about women, chronic illness, and the pain gap reached critical mass.
From Salon ● Jun. 14, 2026
In a fragmented media world where critical mass is becoming harder to attain, Navarro has become one of media’s most recognizable political talking heads thanks to her two high-profile TV roles.
From Los Angeles Times ● May 10, 2026
The situation came to a critical mass in 2024 when Musk sued OpenAI for diverging from its nonprofit mission.
From Slate ● Apr. 30, 2026
The critical mass of plutonium would not stay together long enough to create a massive atomic explosion.
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.
