- critical mass - the minimum amount (of something) required to start or maintain a venture; "the battle for the computer market has now reached critical mass"; "there is now a critical mass of successful women to take the lead"; "they sold the business because it lacked critical mass"
--1 is a kind of amount
- critical mass - the minimum mass of fissionable material that can sustain a chain reaction
--2 is a kind of mass
- critical mass - the minimum mass of fissionable material that can sustain a chain reaction