arcus

[ ahr-kuh s ]

/ ˈɑr kəs /

a dense, horizontal, roll-shaped cloud sometimes occurring at the lower front portion of a cumulonimbus.

Nearby words

< Latin: bow, arch

Also called roll cloud.

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
Otia si tollas, periere Cupidinis arcus—Remove 45 the temptations of idleness, and Cupid's bow is useless.
Dictionary of Quotations from Ancient and Modern, English and Foreign Sources|James Wood
The etymology of arcus is the same; the root arc not only means to hurl, but to sing or resound.
Myth and Science|Tito Vignoli
Its claim, as the parent of projectile implements, is recognized in the common etymology of arcus, arcualia—artillery.
Lippincott's Magazine of Popular Literature and Science Vol. XV., No. 85. January, 1875.|Various

A view of this is given by Donati, who calls it the Arcus Domitiani.
Old Rome|Robert Burn