(ש"ע) אטימות; אי שקיפות; עמימות(של צליל); ערפול; טמטום

n. opaqueness; degree to which something is opaque; obscurity; fuzziness; amount of area on a film that absorbs light (Photography); stupidity

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Noun
1. the phenomenon of not permitting the passage of electromagnetic radiation
(antonym) transparency, transparence
(hypernym) physical phenomenon
(hyponym) optical opacity
2. incomprehensibility resulting from obscurity of meaning
(synonym) opaqueness
(hypernym) incomprehensibility
3. the quality of being opaque to a degree; the degree to which something reduces the passage of light
(synonym) opaqueness
(antonym) clearness, clarity, uncloudedness
(hypernym) quality
(hyponym) cloudiness, murkiness, muddiness
(attribute) opaque

(n.)
The state of being opaque; the quality of a body which renders it impervious to the rays of light; want of transparency; opaqueness.
  

(n.)
Obscurity; want of clearness.
  

The amount of light obscured by particulate pollution in the air; clear window glass has zero opacity, a brick wall is 100 percent opaque. Opacity is an indicator of changes in performance of particulate control systems.