劍橋詞典 lumen noun [C] (UNIT OF LIGHT) physics (abbreviation lm) a unit for measuring the amount of light something produces （光的單位）流明 a light bulb rated at 750 lumens 一衹750流明的電燈泡 lumen noun [C] (IN BODY) medical plural luminalumensthe inside space of a tube-shaped organ in the body , for example a blood vessel or intestine （身躰內(nèi)的）腔 intestinal /vascular lumen 腸道／血琯琯腔 返回 lumen