Dictionary:

REM

  (rĕm)

The rapid, periodic, jerky movement of the eyes during certain stages of the sleep cycle when dreaming takes place.

[R(APID) E(YE) M(OVEMENT).]

A unit of absorbed radiation dose adjusted for biologic effects equivalent to 1 rad of 250 kV x-rays (dental and cephalometric x-rays require less than 100 kV).

On drawings, abbr. for “removable.”

Initialism for "rapid eye movement," a physical phenomenon during which the most active, visually rich, and bizarre dreaming occurs.

Rapid eye movement. See also sleep.