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.


  • (UK) IPA(key): /nɒkˈtɜː(ɹ).nəl/
  • (US) IPA(key): /nɑkˈtɝ.nəl/
  • (file)
  • Rhymes: -ɜː(ɹ)nəl


nocturnal (comparative more nocturnal, superlative most nocturnal)

  1. (of a person, creature, group, or species) Primarily active during the night.
    nocturnal birds
  2. (of an occurrence) Taking place at night, nightly.
    • 2013 January 1, Paul Bartel, Ashli Moore, “Avian Migration: The Ultimate Red-Eye Flight”, in American Scientist[1], volume 101, number 1, page 47–48:
      Many of these classic methods are still used, with some modern improvements. For example, with the aid of special microphones and automated sound detection software, ornithologists recently reported […] that pine siskins (Spinus pinus) undergo an irregular, nomadic type of nocturnal migration.
    a suspicious nocturnal outing


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nocturnal (plural nocturnals)

  1. A person or creature that is active at night.
  2. (historical) A device for telling the time at night, rather like a sundial but read according to the stars.
    Synonym: star clock
    • 2015, David Wootton, The Invention of Science, Penguin 2016, p. 188:
      A rather different instrument was the nocturnal: it enabled you to tell the time at night, provided you knew the date, from the position of the stars in the constellation of the Great Bear, which rotate around the Pole Star.

Old FrenchEdit


nocturnal m (oblique and nominative feminine singular nocturnale)

  1. nocturnal