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

Others don’t mind ambiguity, or even elements of ambiguity’s first cousin, opacity, if there are other things to appreciate. —Michael Phillips, Chicago Tribune, 13 Feb. 2025

The king stares intently into an eternal distance through composite orbs fashioned from alabaster and glass, rendered in varying degrees of clarity, transparency and opacity. —Christopher Knight, Los Angeles Times, 11 Feb. 2025

Allegations of unfair treatment against multiple businesses in a disfavored but legal industry raise concerns about the subjectivity and opacity in banking regulation. —Brady Dale, Axios, 6 Feb. 2025

This opacity allows insurers to deflect accountability while patients face unexpected bills and limited recourse. —Rita Numerof, Forbes, 16 Jan. 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

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)