Of, pertaining to, done or occuring in, the night; as, nocturnal darkness, cries, expedition, etc.; -- opposed to diurnal.

Having a habit of seeking food or moving about at night; as, nocturnal birds and insects; raccoons are nocturnal.; -- of animals.

An instrument formerly used for taking the altitude of the stars, etc., at sea.

Of the night; used in reference to flowers that open after dark.