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.
In the 2010s, conversations about women, chronic illness, and the pain gap reached critical mass.
From Salon • Jun. 14, 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
Until the past decade, what was missing was the good jobs to keep a critical mass of that attractive workforce in the city.
From BBC • Feb. 14, 2026
"It'll hit a critical mass at some point, and maybe become as commonplace as smartwatches or glasses," he said.
From Barron's • Jan. 8, 2026
As more join in, they seem to reach a critical mass, a quorum, and the thinking begins.
From "The Lives of a Cell" by Lewis Thomas
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.
