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

Etymology

Origin of opacity

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

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

Meeks knows when and where to give his lead character distance, respecting that opacity.

From Los Angeles Times ● Aug. 14, 2026

Some analysts, however, argue that opacity in decision-making creates more uncertainty for markets.

From Barron's ● Jul. 26, 2026

“Let me be clear that opacity in this space can be an issue,” he said.

From The Wall Street Journal ● Apr. 23, 2026

The experience of the nonagency mortgage-backed securities market before the 2008 financial crisis shows how opacity can enable misrepresentations of asset quality, erode investor confidence and contribute to market unraveling.

From MarketWatch ● Apr. 13, 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