• synonyms


[ahr-kuh s]
noun, plural ar·cus. Meteorology.
  1. a dense, horizontal, roll-shaped cloud sometimes occurring at the lower front portion of a cumulonimbus.
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Origin of arcus

< Latin: bow, arch
Also called roll cloud.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for arcus

Historical Examples

  • A view of this is given by Donati, who calls it the Arcus Domitiani.

    Old Rome

    Robert Burn

  • Moreover, there is the arcus senilis, the fine translucent to opaque circle surrounding the outer portion of the iris.

    Arteriosclerosis and Hypertension:

    Louis Marshall Warfield

  • The Romans originally called their triumphal arch fornix, not arcus.

    Rambles in Rome

    S. Russell Forbes

  • Otia si tollas, periere Cupidinis arcus—Remove 45 the temptations of idleness, and Cupid's bow is useless.

  • The frustules are curved or arcuate (arcus, a bow) in the side view, oblong and narrowed at the ends in the front view.

arcus in Medicine


n. pl. arcus
  1. A structure resembling a bent bow or an arch.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.