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

That is in part thanks to the opacity of AI technology but also because this clique is much smaller. — Seva Gunitsky, Foreign Affairs, 1 Oct. 2026

The opacity surrounding Zhou has become common practice as Beijing looks to tighten information about key officials in recent years, especially those who serve Xi directly. — Sylvie Zhuang, CNN Money, 30 Sep. 2026

Which is what makes the opacity of the committee's process and evaluation tools so frustrating. — Ian Miller Outkick, FOXNews.com, 29 Sep. 2026

One such product is Biodance’s Bio-Collagen mask, which applies like your average milky white sheet mask but turns clear after a few hours; the opacity change signifies that the ingredients have been absorbed by the skin. — Kiana Murden, Vogue, 25 Sep. 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)