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See also: Onus, ónus, and ônus



Learned borrowing from Latin onus (literally burden).



onus (countable and uncountable, plural onuses or onera)

  1. A legal obligation.
    The onus is on the landlord to make sure the walls are protected from mildew.
  2. (law) Burden of proof, onus probandi.
    • 1883, Henry Drummond, Natural Law in the Spiritual World[1]:
      The argument is founded on a principle which is now acknowledged to be universal; and the onus of disproof must lie with those who may be bold enough to take up the position that a region exists where at last the Principle of Continuity fails.
  3. Stigma.
    • 1993, Dorothy Mermin, Godiva's Ride: Women of Letters in England, 1830-1880, page 19:
      Geraldine evades the onus of ambition by subordinating it to the service of her family, and escapes the onus of sexuality by bodily mutilation
  4. Blame.
    • 1977, Daniel Yergin, Shattered Peace: The Origins of the Cold War and the National Security State, page 6:
      ... what might be called "onus-shifting" — each side trying to make a record and place blame on the other for the division of Europe and the Cold War itself.
  5. Responsibility; burden.
    The onus is on those who disagree with my proposal to explain why.
    • 2000, Beatles with Brian Roylance, Paul McCartney, John Lennon, George Harrison, and Ringo Starr, The Beatles Anthology, page 174:
      The onus isn't on us to produce something great every time. The onus is on the public to decide whether they like it or not.
    • 2023 September 6, Anthony Lambert, “Train paths: more space for freight?”, in RAIL, number 991, page 34:
      This throws the onus on freight operators' train planners to devise ingenious solutions to finding new paths.





Learned borrowing from Latin onus (burden).



onus m (plural onussen or onera, diminutive onusje n)

  1. burden



From Proto-Italic *onos, from Proto-Indo-European *h₃énh₂os, from the root *h₃enh₂-. Cognate with Sanskrit अनस् (ánas, heavy cart; mother; birth; offspring). See Ancient Greek ὄνομαι (ónomai, impugn, quarrel with).



onus n (genitive oneris); third declension

  1. burden, load
    Synonyms: mōlēs, pondus, gravitās
  2. cargo, freight
  3. (figuratively) tax, tax burden


Third-declension noun (neuter, imparisyllabic non-i-stem).

Case Singular Plural
Nominative onus onera
Genitive oneris onerum
Dative onerī oneribus
Accusative onus onera
Ablative onere oneribus
Vocative onus onera

Derived terms[edit]


  • Dutch: onus (learned)
  • English: onus (learned)
  • German: Onus (learned)
  • Italian: onere
  • Sicilian: òniri
  • Portuguese: ónus


  • onus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
  • onus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
  • onus in Charles du Fresne du Cange’s Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
  • onus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.
  • Clackson, James, Indo-European Word Formation: Proceedings from the International Conference, 2002