opacity

noun

opac·​i·​ty ō-ˈpa-sə-tē 

plural opacities

1

a

: obscurity of sense : unintelligibility

b

: the quality or state of being mentally obtuse : dullness

2

: the quality or state of a body that makes it impervious to the rays of light

broadly : the relative capacity of matter to obstruct the transmission of radiant energy

3

: an opaque spot in a normally transparent structure (such as the lens of the eye)

Synonyms of opacity

• ambiguity
• ambiguousness
• mysteriousness
• opaqueness

Examples of opacity in a Sentence

the opacity of the glass

Critics have noted the opacity of her writing style.

Recent Examples on the Web

Image editing is also a strong point, with the ability to resize pictures, change their opacity, adjust their borders, and apply filters and transitions all native to the Web app. —PC Magazine, 18 Nov. 2025

There’s admittedly an opacity to a lot of Nina’s decision-making by the end of the show. —Max Gao, HollywoodReporter, 14 Nov. 2025

The film had the beauty of a travelogue and the opacity of a parable. —Justin Chang, New Yorker, 14 Nov. 2025

By enabling or disabling layers (layout, markers, heat map) and adjusting layer opacity, users get a clear, customizable view of what’s happening—and where to look next. —IEEE Spectrum, 30 Oct. 2025

Word History

Etymology

Middle French opacité shadiness, from Latin opacitat-, opacitas, from opacus shaded, dark

First Known Use

1575, in the meaning defined at sense 1a

Rhymes for opacity

• audacity
• capacity
• loquacity
• mendacity
• pugnacity
• rapacity
• sagacity
• tenacity
• veracity
• vivacity
• voracity
• incapacity

Kids Definition

opacity

noun

opac·​i·​ty ō-ˈpas-ət-ē 

plural opacities

: the quality or state of being opaque

Medical Definition

opacity

noun

opac·​i·​ty ō-ˈpas-ət-ē 

plural opacities

1

: the quality or state of a body that makes it impervious to the rays of light

broadly : the relative capacity of matter to obstruct by absorption or reflection the transmission of radiant energy (as X-rays, infrared radiation, or sound)

2

: an opaque spot in a normally transparent structure (as the lens of the eye)