Definition of “lumen” - English Dictionary

(Definition of “lumen” from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)

“lumen” in American English

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lumennoun [ C ]

/ˈlu·mən/

physics, earth science the standard unit for measuring the brightness of a light, equal to the amount of light hitting one square foot of surface one foot away from the light

(Definition of “lumen” from the Cambridge Academic Content Dictionary © Cambridge University Press)