1. (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
   "The safety guidelines specified exposure limits in rems"

1. A recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep
   "The researchers observed increased brain activity during REM sleep";
   - paradoxical sleep, rapid eye movement sleep, REM sleep, rapid eye movement

Derived forms: rems

Type of: radioactivity unit, shuteye [informal], shut-eye [informal], sleep, slumber

Encyclopedia: Rem