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"
the minimum mass of fissionable material that can sustain a chain reaction
The amount of fissile material needed to support a self-sustaining nuclear chain reaction.
A direct action event in which bicycle riders travel through city streets as a group.