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

Atop all this, understanding the Fed and its decision-making process is becoming much harder, thanks to Fed Chair Kevin Warsh, who is putting a premium on undetailed communications and opacity. — Erik Sherman, Forbes.com, 7 Aug. 2026

Any manicure obsessive can attest to the fact that even the slightest difference in tone, finish, or opacity can completely transform a nail polish. — Ariel Wodarcyk, InStyle, 4 Aug. 2026

This opacity leaves urban planners and residents without the necessary data to make informed choices about their community’s infrastructure, energy usage, and environmental future. — Mrigakshi Dixit, Interesting Engineering, 3 Aug. 2026

As more financing moves into customized private structures, investors and regulators will need to watch for opacity, concentration, and the temptation to confuse financial engineering with genuine economic productivity. — Jim Zelter, Fortune, 31 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)