rem meaning and definition

REM noun

Definition of REM (noun)

1. a recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep
   • synonyms: paradoxical sleep, rapid eye movement, rapid eye movement sleep, REM sleep
2. (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