late 14c., from Old French sompnolence (14c.), from Latin somnolentia "sleepiness," from somnolentus, from somnus "sleep" (from PIE root *swep- "to sleep"). Related: Somnolency.
somnambulation
somnambulism
somni-
somniferous
somniloquy
somnolence
somnolent
Somnus
son
son of a bitch
sonant
