crit·i·cal mass • n. Physics the minimum amount of fissile material needed to maintain a nuclear chain reaction. ∎ fig. the minimum size or amount of something required to start or maintain a venture: a communication system is of no value unless there is a critical mass of users.

critical mass Minimum mass of fissionable material required in a fission bomb or nuclear reactor to sustain a chain reaction. The fissionable material of a fission bomb divides into portions less than the critical mass; when brought together at the moment of detonation they exceed the critical mass. See also fission

Critical Mass ?? 2000 (R)

This one will seem very familiar. Terrorist Samson (Kier) and his crew steal nuclear material and retreat to a deserted nuclear power plant in southern California in order to build a bomb. Only the power plant isn't so deserted and security guard Mike (Williams), aided by babe Janine (Loughlin), work to thwart Samson's nefarious plan. 95m/C VHS, DVD . Treat Williams, Udo Kier, Lori Loughlin, Blake Clark, Andrew Prine; D: Fred Olen Ray; C: Theo Angell; M: Neal Acree. VIDEO

critical critical mass originally, the minimum amount of fissile material needed to maintain a nuclear chain reaction. In extended usage, the minimum size or amount of resources required to start or maintain a venture.
critical path the sequence of stages determining the minimum time needed for an operation, especially when analysed on a computer for a large organization.