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

However, critics argue this lack of transparency could diminish scientific peer review, increase opacity, and potentially open the door to political influence over funding decisions, rather than merit. — Bruce Y. Lee, Forbes.com, 15 Aug. 2026

Meeks knows when and where to give his lead character distance, respecting that opacity. — Robert Abele, Los Angeles Times, 14 Aug. 2026

But to highlight monopolistic opacity is a curious choice of emphasis. — Foreign Affairs, 10 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

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)