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

The filings in the weeks since the election have cut through some of that opacity and shown AIPAC’s allies’ leading role in a surge of outside Congressional primary spending that reached an unprecedented level this cycle. —Dan Petrella, Chicago Tribune, 16 Apr. 2026

The Haitian American singer-songwriter keeps the mood hushed and hazy on his second album, channeling the experimental R&B canon in songs that toggle between sincerity and opacity. —Emma Madden, Pitchfork, 14 Apr. 2026

Another concern is private markets — like derivatives markets, noted for their opacity — which are increasingly intermingled with public markets and have the potential to cause a crash. —Kathryn Anne Edwards, Twin Cities, 14 Apr. 2026

One of the biggest hurdles for elders seeking guidance when the state intervenes in their personal affairs is the opacity of the Florida law governing adult protection. —Carol Marbin Miller, Miami Herald, 2 Apr. 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
• 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)