Somnial acronym

REM

This three-letter term refers to the sleep stage when vivid dreams occur, often linked to rapid eye movements behind closed lids.

Somnial" refers to sleep, so the clue is hinting at a sleep-related acronym. "REM" stands for rapid eye movement, the phase of sleep where most dreaming happens. The wordplay is straightforward—just pairing a fancy term for sleep ("somnial") with a common acronym tied to it.