noun🔗ShareIn the International System of Units, the derived unit of luminous flux; the light that is emitted in a solid angle of one steradian from a source of one candela. Symbol: lm."The new desk lamp provides 800 lumens of light, making it much brighter for studying. "physicsenergytechnicalunitChat with AIVocabulary GamePractice Reading
noun🔗ShareThe cavity or channel within a tube or tubular organ."The doctor inserted a small camera into the artery to examine the lumen for any blockages. "anatomyorganphysiologymedicineChat with AIVocabulary GamePractice Reading
noun🔗ShareThe cavity bounded by a plant cell wall."The plant cell's lumen, visible under the microscope, appeared as a clear space enclosed by the surrounding green cell wall. "biologyplantpartstructureChat with AIVocabulary GamePractice Reading
noun🔗ShareThe bore of a tube such as a hollow needle or catheter."The doctor checked the IV line to make sure the lumen wasn't blocked. "medicineanatomypartdeviceChat with AIVocabulary GamePractice Reading
