Standard Lemma guide

etendue

noun · 1 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.

  • Received-Pronunciation: /ˌeɪ.tɒnˈd(j)uː/
  • Southern-England: Recorded audio is listed in the source snapshot.
  • General-American: /ˌeɪ.tɑnˈdu/
  • rhymes with -uː

1

noun

Meaning 1

A conserved property of the light in an optical system which characterizes how "spread out" the light is in terms of angle and area: it is the product of its cross-sectional area (normal to the direction of propagation) and the solid angle it subtends.

Definition source: English Wiktionary via Wiktextract

Usage: uncountable

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

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: AΩ product, acceptance, geometric extent, light-collecting power, light-gathering power, light grasp, optical extent, throughput

Antonyms: none provided

History

Etymology

Borrowed from French étendue (“area, expanse; size; extent, range, scale”), short for étendue géométrique (“geometric extent”).

Across languages

Translations

7 source translations are retained for this English entry.

  • Bulgarian: геометричен фактор (geometričen faktor) — conserved property of the light in an optical system
  • Finnish: akseptanssi — conserved property of the light in an optical system
  • French: étendue de faisceau — conserved property of the light in an optical system
  • French: étendue géométrique — conserved property of the light in an optical system
  • German: Etendue — conserved property of the light in an optical system
  • Italian: accettanza — conserved property of the light in an optical system
  • Polish: przepustowość — conserved property of the light in an optical system