What does "rapid eye movement" mean?

Fast movement of the eyes, characterising REM sleep

What is a synonym for "rapid eye movement"?

Common synonyms include: paradoxical sleep, rapid eye movement sleep, rem, rem sleep, saccade.

noun

noun ·Rare ·Advanced level

Noun

1
Fast movement of the eyes, characterising REM sleep countable, uncountable
2
a recurring sleep state during which dreaming occurs; a state of rapidly shifting eye movements during sleep wordnet