from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Anatomy The inner open space or cavity of a tubular organ, as of a blood vessel or an intestine.
- n. Physics The unit of luminous flux in the International System, equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions. See Table at measurement.
- n. Botany The cavity bounded by a plant cell wall.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. In 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.
- n. The cavity or channel within a tube or tubular organ.
- n. The cavity bounded by a plant cell wall.
- n. The bore of a tube such as a hollow needle or catheter.
from the GNU version of the Collaborative International Dictionary of English
- n. A unit of illumination, being the amount of illumination of a unit area of spherical surface, due to a light of unit intensity placed at the center of the sphere.
- n. A unit of light flux, being the flux through one square meter of surface the illumination of which is uniform and of unit brightness.
- n. An opening, space, or cavity, esp. a tubular cavity; a vacuole.
from The Century Dictionary and Cyclopedia
- n. An opening or passageway, as, in anatomy, of a hollow tubular organ: as, the lumen of the intestine or of a blood-vessel.
- n. In botany, the internal cavity, or space within the wall, of a cell.
- n. The unit of flux of light; the flux of light in a beam subtending unit solid angle where the source has an intensity of one hefner. See illumination, 1, and light flux.
- n. The hollow tube of an operating-needle or of a hypodermic syringe.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a cavity or passage in a tubular organ
- n. a unit of luminous flux equal to the amount of light given out through a solid angle of 1 steradian by a point source of 1 candela intensity radiating uniformly in all directions
Latin lūmen, an opening, light; see leuk- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)