- (of a cloud) dense enough to obscure the sun or moon.
Origin of opacus
1615–25; < New Latin, Latin opācus; see opaque
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for opacus
The ancestral stock from which A. opacus developed in Micronesia seemingly reached the area from Melanesia.
The structure of its wing resembles that of A. opacus, but the primaries are more rounded.
It has a brown iris, and the immatures lack the streaked underparts which are characteristic of A. opacus and other species.
Niger opacus lvis, clypeo emarginato, thorace postice rotundato, elytrorum lateribus humeralibus haud incisis.
Opacus denotes shady, with reference to a pleasant and beneficial coolness, in opp.Dderlein's Hand-book of Latin Synonymes