/ Dictionary / Index S supercritical: Meaning and Definition of Find definitions for: su•per•crit•i•cal Pronunciation: (s"pur-krit'i-kul), [key] — adj. extremely critical. pertaining to a mass of radioactive material in which the rate of a chain reaction increases with time. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: supercritical (Thesaurus) supercrat supercurrent Related Content Daily Word Quiz: acquiesce Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language