opaque

American  

[oh-peyk] / oʊˈpeɪk /

adjective

1. not transparent or translucent; impenetrable to light; not allowing light to pass through.

   Synonyms:

   muddy, cloudy, murky

2. not transmitting radiation, sound, heat, etc.

3. not shining or bright; dark; dull.

4. hard to understand; not clear or lucid; obscure.

   The problem remains opaque despite explanations.

5. dull, stupid, or unintelligent.

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noun

1. something that is opaque.

2. Photography. a coloring matter, usually black or red, used to render part of a negative opaque.

verb (used with object)

opaqued, opaquing

1. Photography. to cover up blemishes on (a negative), especially for making a printing plate.

2. to cause to become opaque.

opaque British  

/ əʊˈpeɪk /

adjective

1. not transmitting light; not transparent or translucent

2. not reflecting light; lacking lustre or shine; dull

3. not transmitting radiant energy, such as electromagnetic or corpuscular radiation, or sound

4. hard to understand; unintelligible

5. unintelligent; dense

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noun

1. photog an opaque pigment used to block out particular areas on a negative

verb

1. to make opaque

2. photog to block out particular areas, such as blemishes, on (a negative), using an opaque

opaque Scientific  

/ ō-pāk′ /

1. Resistant to the transmission of certain kinds of radiation, usually light. Metals and many minerals are opaque to light, while being transparent to radio waves and neutrinos.

2. Compare translucent transparent

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Other Word Forms

• opaquely adverb
• opaqueness noun
• subopaque adjective
• subopaquely adverb
• subopaqueness noun

Etymology

Origin of opaque

First recorded in 1375–1425; late Middle English opake, from Latin opācus “shaded”

Explanation

Use the adjective opaque either for something that doesn't allow light to pass through (like a heavy curtain) or for something difficult to understand (like bureaucratic gobbledygook). Opaque is from a Latin word meaning "dark," and that was its original sense in English, but it now means literally "not transparent" or metaphorically "hard to understand; unclear": "Some of his sentences are really opaque." It used to be spelled opake, which made the pronunciation clearer, but we then borrowed the more opaque French spelling. Come to think of it, English spelling is often pretty opaque, which makes it hard for learners of the language to master.

Example Sentences

In the opaque and expensive U.S. healthcare system, where costs are rapidly rising, people are increasingly landing in the nascent DIY healthcare shopping economy.

From The Wall Street Journal • Apr. 18, 2026

Private-credit providers extend financing to companies in relatively opaque transactions, and the practice has boomed over the past few years.

From MarketWatch • Apr. 14, 2026

"The financial costs of industrial action in the NHS are fairly opaque," said Sally Gainsbury of the Nuffield Trust.

From BBC • Apr. 13, 2026

For instance, they might think they want a Booker Prize finalist, only to find it infuriatingly opaque.

From Los Angeles Times • Apr. 9, 2026

They look sort of like the slimmed-down opaque wraparound shades worn by cyclists.

From "A Deadly Wandering: A Mystery, a Landmark Investigation, and the Astonishing Science of Attention in the Digital Age" by Matt Richtel

Related Words

• blurred
• cloudy
• dirty
• dull
• frosty
• gloomy
• hazy
• impenetrable
• murky
• thick