lumen
noun [ C ] specialized uk/ˈluː.mən/ us/ˈluː.mən/
(UNIT OF LIGHT)
physics (abbreviation lm)（光的单位）流明
a unit for measuring the amount of light something produces
a light bulb rated at 750 lumens 一只750流明的电灯泡
(IN BODY)
medical plural lumina or lumens（身体内的）腔
the inside space of a tube-shaped organ in the body, for example a blood vessel or intestine
intestinal/vascular lumen 肠道／血管管腔