opacity

American  

[oh-pas-i-tee] / oʊˈpæs ɪ ti /

noun

• opacities
  plural

1. the state or quality of being opaque.

2. something opaque.

3. the degree to which a substance is opaque; capacity for being opaque.

4. Photography. the proportion of the light that is absorbed by the emulsion on any given area of a film or plate.

5. obscurity of meaning.

6. mental dullness.

7. Medicine/Medical. an opaque spot or area in normally clear or transparent tissue, as a cataract of the eye.

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opacity British  

/ əʊˈpæsɪtɪ /

noun

1. the state or quality of being opaque

2. the degree to which something is opaque

3. an opaque object or substance

4. obscurity of meaning; unintelligibility

5. physics photog the ratio of the intensity of light incident on a medium, such as a photographic film, to that transmitted through the medium

6. logic philosophy the property of being an opaque context

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Other Word Forms

Derived Forms

• nonopacity
  noun

Inflected Forms

Nouns

• opacities
  plural

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Etymology

Origin of opacity

First recorded in 1550–60, opacity is from the Latin word opācitās shade. See opaque, -ity

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Explanation

Opacity is the characteristic of being difficult to understand or unclear. A professor whose lectures are known for opacity is going to find himself in a room full of some very frustrated students. In its literal sense opacity is used to talk about objects that don't allow light to shine through. A window that has accumulated a lot of dirt and dust is characterized by its opacity, as opposed to a transparent window, which is one you can see right through. The word opacity is used more generally for anything obscure, unclear, or incomprehensible, like the opacity of a novel full of ten-syllable words or a dictionary that doesn't give you any clear or straightforward definitions.

Example Sentences

See Examples For:

opacity opacities

The US firm said earlier this year that investors had raised concerns about "ongoing opacity in shareholding structures" as well as co-ordinated trading behaviour that affected price information.

From Barron's ● Oct. 16, 2026

Such opacity makes the ships difficult to police.

From Los Angeles Times ● Oct. 9, 2026

But if it’s part of a larger pattern of opacity, instability and conflicting messaging, something larger might be coming down the pike.

From MarketWatch ● Jun. 12, 2026

Prime Minister Pedro Sanchez's government and the Catholic Church in Spain signed an agreement in March to compensate victims, after years of reticence and opacity from the Church hierarchy.

From Barron's ● Jun. 8, 2026

He was instantly struck by the opacity of an investment bank’s books.

From "The Big Short" by Michael Lewis

Ground-glass opacities — a sign that’s common in COVID-19 patients — showed up on his scans.

From Los Angeles Times ● Mar. 31, 2025

When Sovannarie was 3 months old, her parents noticed something unusual about their daughter: white opacities in both pupils.

From Salon ● Dec. 11, 2022

The panels come in different opacities — some are clear, while others block more UV light for sun protection.

From Seattle Times ● Mar. 25, 2021

“Don’t Believe a Word,” a new book by the Guardian writer and editor David Shariatmadari, delves into the riddles of language: the opacities, ambushes, dead ends, sudden ecstasies.

From New York Times ● Jan. 1, 2020

"The material simply admits all light-vibrations, or perhaps curves them, just as the opacities cut them off," I answered.

From The Moon Pool by Abraham Merritt

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