/ Dictionary / Index R reins: Meaning and Definition of Find definitions for: reins Pronunciation: (rānz), [key] the kidneys. the region of the kidneys, or the lower part of the back. (esp. in Biblical use) the seat of the feelings or affections, formerly identified with the kidneys. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: reins (Thesaurus) Reinhold reinsman 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