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

That kind of opacity would be a problem for almost any other organization with a similar mandate. — Literary Hub, 17 July 2026

These sentences are part of a four-plus-page descriptive riff, one of many passages that lend the novel a teeming, avid opacity. — Richard Brody, New Yorker, 9 July 2026

An American expat who has fully embraced British eccentricity and emotional opacity, Kimi Murdoch could be a Toni Collette character. — Judy Berman, Time, 8 July 2026

With hundreds of shades, finishes, and opacities to choose from, the nail polish for you really comes down to preference. — Conçetta Ciarlo, Vogue, 7 July 2026

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
• fugacity
• loquacity
• mendacity
• 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)