/ Dictionary / Index R rejection region: Meaning and Definition of Find definitions for: rejec'tion re"gion Pronunciation: [key] — Statistics. Statistics. the set of values of a test statistic for which the null hypothesis is rejected. Cf. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rejectionist rejection slip Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language