Nocturnal means active at night and asleep by day. A nocturnal animal, nocturnal habits, nocturnal hunting.
Being nocturnal is mostly about avoiding something — heat, or predators, or competition — rather than preferring the dark. Most mammals are, which is thought to be why colour vision is poor in so many of them. The Latin nox means night.
1adjectivenocturnalActive at night and asleep by day.
“Hedgehogs are nocturnal, so you're most likely to see one in the garden after dark.”
nocturnal is a habit of activity.
Latin nocturnalis comes from nox, night. Nocturne and equinox share the same night.
Latin
nocturnālis — nocturnal
Middle French
nocturnal
English, today
nocturnal
From Middle French nocturnal, from Latin nocturnālis (“nocturnal”), from Latin nocturnus (“nocturnal”), from Latin nox (“night”), from Proto-Indo-European nókʷts (“night”). Cognates include Ancient Greek νύξ, Sanskrit नक्ति, Old English niht (English night) and Proto-Slavic noťь.
Etymology from Wiktionary, CC BY-SA