opacus

[ oh-pey-kuh s ]
/ oʊˈpeɪ kəs /
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adjective Meteorology.

(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. 2019

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