mid-15c., sompnolent, from Old French sompnolent (Modern French somnolent) or directly from Latin somnolentus "sleepy, drowsy," from somnus "sleep" (from PIE root *swep- "to sleep"). Respelled 17c. on Latin model.
the sound had a somnolent effect
somnambulism
somni-
somniferous
somniloquy
somnolence
somnolent
Somnus
son
son of a bitch
sonant
sonar