/ Dictionary / Index R rem: Meaning and Definition of Find definitions for: rem Pronunciation: (rem), [key] the quantity of ionizing radiation whose biological effect is equal to that produced by one roentgen of x-rays. REM Pronunciation: (rem), [key] — n. See Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: rem (Thesaurus) rely remain 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