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English definition of “lumen”

lumen

noun [C] uk   /ˈluː.mən/ us    // specialized

lumen noun [C] (unit of light)

(abbreviation lm) physics a unit for measuring the amount of light something produces: a light bulb rated at 750 lumens

lumen noun [C] (in body)

(plural lumina or lumens) medical the inside space of a tube-shaped organ in the body, for example a blood vessel or intestine: intestinal/vascular lumen
(Definition of lumen from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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