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| lu·men [ lmən ] (plural lu·mens or lu·mi·na [ lmənə ]) |
noun |
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| Definition: |
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1. unit of luminous flux: the SI unit of luminous flux, equal to the amount of light crossing a unit area at a unit distance from a light source of luminous intensity of one candela. Symbol lm
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2. space within tube: the space inside any tubular structure in the body such as an intestine, artery, or vein
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3. cavity in plant: the cavity within a plant cell wall
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| [Late 19th century. < Latin, "light, opening"] |
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