Meaning of critical mass

crit'ical mass'

Pronunciation: [key]
  1. the amount of a given fissionable material necessary to sustain a chain reaction at a constant rate.
  2. an amount necessary or sufficient to have a significant effect or to achieve a result: a critical mass of popular support.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.