foot-lambert or foot·lam·bert [foo t-lam-bert] Word Origin noun Optics.
- a unit of luminance or photometric brightness, equal to the luminance of a surface emitting a luminous flux of one lumen per square foot, the luminance of a perfectly reflecting surface receiving an illumination of one foot-candle. Abbreviation: fL
Origin of foot-lambert First recorded in 1920–25 British Dictionary definitions for foot-lambert foot-lambert noun
- a former unit of luminance equal to the luminance of a surface emitting or reflecting 1 lumen per square foot. A completely reflecting surface illuminated by 1 foot-candle has a luminance of 1 foot-lambertAbbreviation: ft-L