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

• ambiguity
• ambiguousness
• darkness
• equivocalness
• equivocation
• inscrutability
• inscrutableness
• murkiness
• mysteriousness
• nebulosity
• nebulousness
• obliqueness
• obliquity
• obscurity
• 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

Increasing bipartisan scrutiny and pressure to lower drug prices generally threaten the opacity of their business model, potentially sparking further consolidation as legacy PBMs scramble to defend market share and margins. —Steven Dudash, Forbes.com, 30 May 2025

And an X-ray of his chest was worrisome—there were diffuse ground-glass opacities in his lungs. —Beth Mole, ArsTechnica, 28 May 2025

The movie’s psychological framework, its system of motivations, is stretched very thin between two extremes: of clarity and opacity, near-obviousness and absolute impenetrability. —Richard Brody, New Yorker, 28 May 2025

Other firsts include a smart-glass roof featuring four quadrants for passengers to control opacity, and electronic shutters that obscure screen content while driving and can be controlled remotely via a QR code on the phone. —Jaclyn Trop, Robb Report, 21 May 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)