The smallest amount of fissile material needed for a sustained nuclear chain reaction.
the minimum mass of fissionable material that can sustain a chain reaction
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 c
the minimum amount (of something) required to start or maintain a venture
