/ Dictionary / Index C critical ratio: Meaning and Definition of Find definitions for: crit'ical ra'tio Pronunciation: [key] — Statistics. Statistics. a ratio associated with the probability of a sample, usually the ratio of the deviation from the mean to the standard deviation. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. critical pressure critical region Related Content Daily Word Quiz: cautious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language