Added 2 October 2026
opacity
/oʊˈpæsɪti/ noun
Latin root: opācitās Wiktionary
noun Definition from Wiktionary (CC BY-SA). Pronunciation from Wiktionary, via Kaikki.org. More about opacity at Wordnik → Where our words come from →
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The state or quality of being opaque, not allowing light to pass through.
We could not see the sandbar due to the opacity of the muddy water.
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The state or quality of being inaccessible to understanding.
The opacity of these decisions is troubling.
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A measure of relative impenetrability to electromagnetic radiation such as light.
The opacity of a clean glass window is near zero.
Origin
From opaque + -ity, from French opacité, from Latin opācitās, from opācus.
From Wiktionary, via Kaikki.org (CC BY-SA)