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.

---

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

---

Etymology

Origin of critical mass

First recorded in 1940–45

Example Sentences

See Examples For:

critical mass

“These two equilibria are self-fulfilling. As soon as a critical mass of bondholders believe they are in a given equilibria their behavior assures that they are!”

From The Wall Street Journal ● Sep. 29, 2026

This is the broken link in the chain between a critical mass of American Jews and the faith’s biggest domestic organizations.

From Slate ● Sep. 16, 2026

The model of Manchester's city centre development has succeeded in creating a critical mass of population, housing, jobs and service sector activity that has allowed it to turn its significant undergraduate population into a goldmine.

From BBC ● Jul. 17, 2026

Scientists need a critical mass of data to be able to identify statistically significant patterns.

From Los Angeles Times ● Jun. 15, 2026

If he was avoiding the critical mass of Bahramis by taking shelter in the kitchen.

From "Darius the Great Is Not Okay" by Adib Khorram