English
etendue
Etendue comes from French étendue ‘area, expanse’.
- Frenchc. 1600–presentétendue‘area, expanse’
- Englishearliest quotation 1966etendue
attested reconstructed ? uncertain or disputed
Lineage
- Frenchc. 1600–presentétendue‘area, expanse’
- Englishearliest quotation 1966etendue
Earliest quotation: 1966, Advanced Infrared Technology [course title]: “The topics include […] carefully outlining the concepts of…”
Every English word from French étendue
Today it means
noun 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.
Language periods are conventional ranges, not dates for this word.
Etymograph / French étendue / etendue