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Shelf cloud, a type of arcus


Borrowed from Latin arcus. Doublet of arc and arco. Distantly related to arrow.


arcus (plural arcus)

  1. (medicine) A white band of cholesterol that forms at the edge of the cornea
  2. (meteorology) A low, horizontal cloud typically forming at the leading edge of thunderstorm outflow
  3. (entomology) An elastic band around the base of the arolium, a pad at the end of the leg of certain insects
  4. (palynology) An arc-shaped band of thickened sexine extending between two apertures on a pollen grain or spore

Related terms[edit]




Latin Wikipedia has an article on:
Wikipedia la


From Proto-Indo-European *h₂erkʷos (bow, arrow). Cognate to Old English earh, whence English arrow.



arcus m (genitive arcūs); fourth declension

  1. arc, arch
  2. bow (arc-shaped weapon used for archery)
  3. rainbow


Fourth-declension noun (dative/ablative plural in -ubus).

Case Singular Plural
Nominative arcus arcūs
Genitive arcūs arcuum
Dative arcuī arcubus
Accusative arcum arcūs
Ablative arcū arcubus
Vocative arcus arcūs

Derived terms[edit]

Related terms[edit]


  • Albanian: hark
  • Aromanian: arcu
  • English: arch
  • Esperanto: arko
  • Old French: arc
  • Padanian:
  • Romansch: artg, arch
  • Middle Low German: ark
    • Low German: ark
      • Norwegian Bokmål: ark
  • Occitano-romance:
  • Romanian: arc
  • Russian: а́рка f (árka)
  • Sardinian: alcu, arcu
  • Italo-Dalmatian:
  • Ibero-romance:

See also[edit]


  • arcus”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
  • arcus”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
  • arcus 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)
  • arcus in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette
  • arcus”, in Harry Thurston Peck, editor (1898) Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers
  • arcus in Ramminger, Johann (accessed 16 July 2016) Neulateinische Wortliste: Ein Wörterbuch des Lateinischen von Petrarca bis 1700[1], pre-publication website, 2005-2016
  • arcus”, in William Smith et al., editor (1890) A Dictionary of Greek and Roman Antiquities, London: William Wayte. G. E. Marindin