noun

opacity

oh-PASS-ih-tee

Opacity (noun) means the degree to which something blocks light or cannot be seen through; the quality of being opaque. Example: “Increase the opacity of the layer until the watermark disappears.”

noun

The degree to which something blocks light or cannot be seen through; the quality of being opaque.

"Increase the opacity of the layer until the watermark disappears."

"The glass is treated to give it enough opacity for a bathroom window."

In graphics software and CSS, a numerical setting controlling how solid an element appears, where the maximum value is fully solid and zero is invisible.

"Set the overlay to 0.6 opacity so the photo still reads underneath."

"At 50% opacity the drop shadow looks far more natural."

The quality of being obscure, hard to understand or deliberately unclear.

"The opacity of the funding arrangements is what worries auditors most."

How to Use Opacity

Learner’s notes

In plain EnglishHow solid or see-through something is.

When to use it

Neutral; equally at home in physics, design software and political criticism.

Memory tip

Stress the second syllable: oh-PASS-ih-tee. The adjective is opaque, pronounced oh-PAYK.

Trace the full origin ↓

Easily confused with

transparency → translucency alpha →

Common pairings

reduce the opacity full opacity opacity slider opacity of the process

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Fill the Gap

Can you complete this real example?

Increase the _____ of the layer until the watermark disappears.

Etymology

From Latin opacitas 'shadiness', from opacus 'shaded, dark', by way of French opacité.

Origin: Latin

Synonyms

View more →

density cloudiness impenetrability obscurity murkiness

Antonyms

transparency translucency clarity

Related Words

clear intelligence concentration density darkness confusion transparency clarity

Rhymes for opacity

city pity deity acuity parity entity brevity paucity ability quality reality annuity

See all rhymes for opacity →

Frequently Asked Questions

What is the difference between opacity and transparency?

They are opposite ends of the same scale: opacity measures how much light is blocked, transparency how much passes through. In design software raising opacity to 100% makes an element fully solid, which is the same as zero transparency.

What does opacity 0.5 mean in CSS?

It renders the element at half strength, so whatever sits behind it shows through. CSS opacity runs from 0 (completely invisible but still occupying its space) to 1 (completely solid), and it applies to the element's children as well, which is why a semi-transparent background colour is often the better choice.

What is opacity on a chest X-ray?

In radiology an opacity is an area that appears whiter than the surrounding tissue because it is blocking more X-rays, which can indicate fluid, inflammation or a mass. The term describes the appearance on the image, not a diagnosis.

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