- of or relating to the night (opposed to diurnal).
- done, occurring, or coming at night: nocturnal visit.
- active at night (opposed to diurnal): nocturnal animals.
- opening by night and closing by day, as certain flowers (opposed to diurnal).
- Archaic. an astrolabe for telling time at night or for determining latitude by the position of certain stars in reference to Polaris.
- of, used during, occurring in, or relating to the night
- (of animals) active at night
- (of plants) having flowers that open at night and close by day
adj.late 15c., from Old French nocturnal “nightly, nocturnal,” or directly from Late Latin nocturnalis, from Latin nocturnus “belonging to the night,” from nox (genitive noctis) “night,” cognate with Old English neaht (see night) + -urnus, suffix forming adjectives of time. Nocturnal emission “involuntary ejaculation during sleep” first recorded 1813. adj.
- Of, relating to, or occurring in the night.
- Most active at night.
- Occurring at night.
- Most active at night. Many animals, such as owls and bats, are nocturnal.
- Having flowers that open during the night and close at daylight. Nocturnal plants are often pollinated by moths. Compare diurnal.