rem (Adjective) — (formal) pertinent; relevant.
rem (Noun) — (law) a judgment pronounced on the status of some particular subject, property or thing (as opposed to one pronounced on persons).
rem (Noun) — A recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep.
rem (Noun) — (Roentgen Equivalent Man) the dosage of ionizing radiation that will cause the same amount of injury to human tissue as 1 roentgen of X-rays.