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

But such opacity does not erase the commercial logic of releasing the weights. — Jacek Krywko, Scientific American, 23 July 2026

The lack of rights owed to victims in particular has been repeatedly condemned by international commissions and inquests into clergy abuse that have found that the church’s judicial procedures retraumatize victims through their secrecy and opacity. — ABC News, 22 July 2026

Records from Delaware, a state known for offering incorporators a large degree of opacity, show the Freedom Fuel Network was registered on June 23. — Brian Slodysko, Fortune, 20 July 2026

Company formed in a state known for opacity Records from Delaware, a state known for offering incorporators a large degree of opacity, show the Freedom Fuel Network was registered on June 23. — Brian Slodysko, Los Angeles Times, 20 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)