lumen

  1. Noun.  (physics) In the International System of Units, the derived unit of luminous flux; the amount of light that falls on a unit area at unit distance from a source of one candela. Symbol: lm.
  2. Noun.  (anatomy) The cavity or channel within a tube or tubular organ.
  3. Noun.  (botany) The cavity bounded by a plant cell wall.
  4. Noun.  (medicine) The bore of a tube such as a hollow needle or catheter.

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This entry was last updated on RefTopia from its source on 3/20/2012.