Standard Lemma guide

opacity

noun · 7 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • US: ōpăsʹĭti
  • US: /oʊˈpæsɪti/
  • US: Recorded audio is listed in the source snapshot.
  • CMU ARPABET: OW0 P AE1 S AH0 T IY0 Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.

1

noun

Meaning 1

The state or quality of being opaque, not allowing light to pass through.

Definition source: English Wiktionary via Wiktextract

Usage: uncountable

Examples

  • We could not see the sandbar due to the opacity of the muddy water.

Meaning relationships

Synonyms: opaqueness, nontransparency

Antonyms: clarity, clearness, translucency, transparency

2

noun

Meaning 2

The state or quality of being inaccessible to understanding.

Definition source: English Wiktionary via Wiktextract

Usage: uncountable

Examples

  • The opacity of these decisions is troubling.

Meaning relationships

Synonyms: none provided

Antonyms: clarity, lucidity

3

noun

Meaning 3

A measure of relative impenetrability to electromagnetic radiation such as light.

Definition source: English Wiktionary via Wiktextract

Usage: countable

Topics: engineering, natural-sciences, optics, physical-sciences, physics

Examples

  • The opacity of a clean glass window is near zero.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

4

noun

Meaning 4

An opaque area.

Definition source: English Wiktionary via Wiktextract

Usage: countable

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

5

noun

Meaning 5

the quality of being opaque to a degree; the degree to which something reduces the passage of light

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: opaqueness

Antonyms: clarity

Broader terms: quality

Narrower terms: cloudiness, murkiness, muddiness, indistinctness, softness, blurriness, fogginess, fuzziness

6

noun

Meaning 6

incomprehensibility resulting from obscurity of meaning

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: opaqueness

Antonyms: none provided

Broader terms: incomprehensibility

7

noun

Meaning 7

the phenomenon of not permitting the passage of electromagnetic radiation

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: transparency

Broader terms: physical phenomenon

Narrower terms: optical opacity, radiopacity, radio-opacity

History

Etymology

From opaque + -ity, from French opacité, from Latin opācitās, from opācus.

Across languages

Translations

36 source translations are retained for this English entry.

  • Belarusian: непразры́стасць (njeprazrýstascʹ) — state of being opaque; blocking light
  • Bulgarian: непрозрачност (neprozračnost) — state of being opaque; blocking light
  • Catalan: opacitat — state of being opaque; blocking light
  • Czech: neprůhlednost — state of being opaque; blocking light
  • Danish: uigennemsigtighed — state of being opaque; blocking light
  • Danish: ugennemsigtighed — state of being opaque; blocking light
  • Finnish: läpikuultamattomuus — state of being opaque; blocking light
  • Finnish: läpinäkymättömyys — state of being opaque; blocking light
  • French: opacité — state of being opaque; blocking light
  • Galician: opacidade — state of being opaque; blocking light
  • German: Opazität — state of being opaque; blocking light
  • German: Undurchsichtigkeit — state of being opaque; blocking light
  • German: Lichtundurchlässigkeit — state of being opaque; blocking light
  • Greek: αδιαφάνεια (adiafáneia) — state of being opaque; blocking light
  • Hindi: अपारदर्शिता (apārdarśitā) — state of being opaque; blocking light
  • Indonesian: ketidakbeningan — state of being opaque; blocking light
  • Latvian: necaurredzamība — state of being opaque; blocking light
  • Latvian: necaurspīdīgums — state of being opaque; blocking light
  • Norwegian Bokmål: opasitet — state of being opaque; blocking light
  • Norwegian Bokmål: ugjennomsiktighet — state of being opaque; blocking light
  • Portuguese: opacidade — state of being opaque; blocking light
  • Russian: непрозра́чность (neprozráčnostʹ) — state of being opaque; blocking light
  • Spanish: opacidad — state of being opaque; blocking light
  • Swedish: opacitet — state of being opaque; blocking light
  • Tagalog: opasidad — state of being opaque; blocking light
  • Ukrainian: непрозо́рість (neprozóristʹ) — state of being opaque; blocking light
  • Bulgarian: неясност (nejasnost) — state of being inaccessible to understanding
  • French: opacité — state of being inaccessible to understanding
  • German: Undurchsichtigkeit — state of being inaccessible to understanding
  • German: Nebulösität — state of being inaccessible to understanding
  • Tagalog: opasidad — state of being inaccessible to understanding
  • Finnish: läpikuultamattomuus — measure of relative opaqueness
  • Finnish: läpinäkymättömyys — measure of relative opaqueness
  • Indonesian: ketidakbeningan — measure of relative opaqueness
  • Tagalog: opasidad — measure of relative opaqueness
  • Ukrainian: помутні́ння (pomutnínnja) — opaque area