Etymology

etendue

eten·due
E1T1E1N1D2U1E1

Today it means: 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. Full definition →

French étendue
Ask AI about its historyChatGPTClaudePerplexityGoogle AIGrok

The story

  1. French · borrowed frométendue“area, expanse; size; extent, range, scale”
  2. English todayetendue

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

Etymology from Wiktionary, CC BY-SA 4.0.