critical_mass
1. [ noun ] the minimum amount (of something) required to start or maintain a venture
Examples:

"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

Related terms: amount
2. [ noun ] the minimum mass of fissionable material that can sustain a chain reaction
Related terms: mass
Similar spelling:   criticalness
  critically
  critical_point
  critical_angle
  criticality
  critical_review