n. a property of the light in an optical system; the product of its cross-sectional area (normal to the direction of propagation) and the solid angle it subtends.
Word Usage
"You gave me a flower and said it was “plus petite et moins etendue”—67We were friends—Then you took it away and I grew sicker, and there was nobody to teach me, so here I am, after five months of misery and agony and desperation."