nocturnal

Etymology

It is borrowed from Late Latin nocturnālis (“of the night”),^[2][3][4][5] a word recorded from the 5th century;^[2] Barnhart, Etymonline and Merriam-Webster also allow a borrowing from Middle French nocturnal.^[6][7][8] The OED compares Anglo-Norman and Old French nocturnel and nocturnal, and notes that modern French nocturnal is apparently a late 18th-century reborrowing.^[2] The Latin adjective is formed from nocturnus (“belonging to the night”) and -ālis,^[2][8] and nocturnus from nox (“night”) with -urnus, a suffix of adjectives of time.^[7][9] The Latin noun is cognate with Old English neaht, the source of night,^[7] and goes back to Proto-Indo-European *nekʷ-t- (“night”).^[10]

Earliest recorded meaning

Of the night, done or held at night: 1485, in Caxton's translation of the Lyf of Saint Wenefryde, in the phrase nocturnal office.^[2][6][7] The OED compares post-classical Latin nocturnale officium.^[2]

Semantic evolution

The word was used of animals active chiefly at night from 1599,^[2] of people active at night from 1679, in Aphra Behn,^[2] and of eyes adapted to night vision from 1840.^[2] Johnson (1755) glossed it simply as "nightly", quoting Dryden.^[11] Nocturnal emission, an involuntary ejaculation in sleep, is recorded by 1813.^[7][4] As a noun it named, from 1582, a mainly nautical instrument for telling the time at night from the stars, after German Nocturnal;^[2][8] a night piece from 1607, in Marston;^[2] and a person out at night, especially for a criminal purpose, from 1693.^[2][8] The OED also records the variant noctural, perhaps remodelled after natural.^[2]

Timeline

• 1485 – of or relating to the night, in Caxton.^[2][6]
• 1582 – noun, an instrument for telling the time at night.^[2]
• 1599 – of animals, active chiefly at night.^[2]
• 1607 – noun, a night piece.^[2]
• 1679 – of a person, active at night.^[2]
• 1693 – noun, a person out at night.^[2]
• 1813 – nocturnal emission.^[7]
• 1840 – of an eye, adapted for night vision.^[2]

Meanings

Adjective

1. Of, relating to, happening or done at night: nocturnal noises from the attic.^[5][8][2]
2. Of animals, active mainly at night; compare diurnal.^[5][8][2]
3. Of plants, having flowers that open at night and close by day.^[5][8]
4. Of a person, active at night or preferring to be.^[2]

Noun

1. (historical) An astrolabe-like instrument for finding the time or the latitude at night from the stars.^[8][2]
2. A night piece.^[8][2]
3. One who is out or active at night; a nightwalker.^[8][2]

Word family

• nocturnally
• nocturnality
• seminocturnal
• nonnocturnal
• nocturnal arc
• nocturnal emission

Related words

• night
• nocturn
• nocturne
• diurnal

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
4. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
5. ^ a b c d Collins English Dictionary (2023), Glasgow: HarperCollins
6. ^ a b c Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
7. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
8. ^ a b c d e f g h i j Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
9. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
10. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.