somnolent
- Feeling drowsy and inclined to sleep; also, having a sleep-inducing quality.
In a sentence
- The warm afternoon and the hum of the ceiling fan left the students somnolent and barely able to take notes.
- The documentary's somnolent narration made it nearly impossible to stay awake past the first half hour.
Usage note. Somnolent can describe both a person who is sleepy and an environment or thing that induces sleepiness; 'the somnolent heat of the afternoon' is therefore perfectly correct.
Where it comes from
English somnolent — “drowsy, sleep-inducing” · entered English 15th c.
From Latin 'somnolentus', meaning 'sleepy' or 'drowsy', derived from 'somnus', meaning 'sleep', which traces to the Proto-Indo-European root '*swep-' meaning 'to sleep'. The Latin 'somnus' is related to Greek 'hypnos' (sleep) and Sanskrit 'svapna'. The word entered English in the 15th century via learned Latin usage.