1. (a.) Pertaining to the night; as, nocturnal darkness, cries, expedition; -- opposed to diurnal\.

2. (a.) Having a habit of seeking food or moving about at night; as, nocturnal birds and insects.

3. (n.) An instrument formerly used for taking the altitude of the stars, etc., at sea.

all-night atramentous black black as coal black as ebony black as ink black as midnight black as night coal-black coaly dark dark as night dark as pitch dead of night deep black ebony hush of night ink-black inky jetty night night-black night-dark night-fallen nightlong nightly nighttime nigrous nocturnal noonday night pitch-black pitch-dark pitchy raven raven-black sable sloe sloe-black sloe-colored tar-black tarry