critical mass

American  

[krit-i-kuhl mas] / ˈkrɪt ɪ kəl ˈmæs /

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.

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critical mass British  

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

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Etymology

Origin of critical mass

First recorded in 1940–45

Example Sentences

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

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

At one point Karp tried to rally the troops and attempted to organize a joint letter, but a critical mass wouldn’t sign on.

From The Wall Street Journal • Feb. 6, 2026

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

Which means that in the suburbs and exurbs it’s hard to generate the critical mass needed to ignite truly bad behavior.

From "Dry" by Neal Shusterman and Jarrod Shusterman