Etendue
noun ·Rare ·Advanced level
Definitions
- 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. uncountable
"The topics include […] carefully outlining the concepts of etendue, finesse, and their theoretical implications; methods of spectral, spatial, temporal, and polarization discrimination; and application of these topics to search and track systems."
Example
More examples"The topics include […] carefully outlining the concepts of etendue, finesse, and their theoretical implications; methods of spectral, spatial, temporal, and polarization discrimination; and application of these topics to search and track systems."
Etymology
Borrowed from French étendue (“area, expanse; size; extent, range, scale”), short for étendue géométrique (“geometric extent”).
Related phrases
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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.