English Reference
adjective · noun

nocturnal

adj. · n.
US /nɑkˈtɝnəɫ/ UK /nɒktˈɜːnəl/ noc·tur·nal

  1. 01 B2 Upper Intermediate Science

    adj.describes animals or people that are awake and active at night instead of during the day.

    adj.relating to or characteristic of animals that are active during the night and sleep during the day.

    Simple

    Owls are nocturnal hunters that use their excellent hearing to find food in the dark.

    In context

    Many desert mammals have evolved nocturnal habits to avoid the intense heat of the midday sun.

    night loving
  2. 02 C1 Advanced Formal

    adj.happening or done during the night.

    adj.occurring, done, or active at night; often used in formal or technical descriptions of events.

    Simple

    The city was quiet except for the occasional nocturnal sounds of traffic.

    In context

    The poet was inspired by the nocturnal silence of the countryside, which stood in stark contrast to the chaos of London.

  3. 03 C2 Proficiency ArchaicTechnical Science

    n.an old tool used in the past to tell the time at night by looking at the stars.

    n.an instrument formerly used for determining the time of night by the positions of certain stars.

    Simple

    The museum has a brass nocturnal used by sailors in the seventeenth century.

    In context

    Before the invention of reliable mechanical clocks, the nocturnal provided navigators with a means to determine the time using the North Star.

They were small and had long bodies, eyes typical of nocturnal mammals and small, spiky teeth for eating insects.

Phys.org· 3 Sept 2026

From Middle French nocturnal, from Latin nocturnus (“nocturnal, nightly”), from Latin nox (“night”), from Proto-Indo-European nókʷts (“night”). Cognates include Ancient Greek νύξ (núx), Sanskrit नक्ति (nákti), Old English niht (English night) and Proto-Slavic noťь.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin ine-pro *nókʷts
Level B2 · Upper Intermediate
Frequency Frequent
Updated