lumen

[loo-muh n] /ˈlu mən/
noun, plural lumens, lumina
[loo-muh-nuh] /ˈlu mə nə/ (Show IPA)
1.
Optics. the unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity.
Abbreviation: lm.
2.
Anatomy. the canal, duct, or cavity of a tubular organ.
3.
Botany. (of a cell) the cavity that the cell walls enclose.
Origin
1870-75; < New Latin, special uses of Latin lūmen (stem lūmin-) light, window
Examples from the web for lumen
  • The walls were thicker than normal, the inner lumen almost completely obliterated.
  • They must be sealed to avoid moisture and kept clean to maintain lumen maintenance.
  • The light perceived by the human eye is measured in units called lumen-hours.
  • The nuclei alternate on opposite surfaces of the tubule so that the lumen remains fairly constant.
  • The movements of the jaw influence to some extent the lumen of this latter portion.
  • lumen maintenance strategies have only recently become economically viable for general use.
  • With more protons inside the lumen than the stroma, the pH is much lower inside the lumen.
British Dictionary definitions for lumen

lumen

/ˈluːmɪn/
noun (pl) -mens, -mina (-mɪnə)
1.
the derived SI unit of luminous flux; the flux emitted in a solid angle of 1 steradian by a point source having a uniform intensity of 1 candela lm
2.
(anatomy) a passage, duct, or cavity in a tubular organ
3.
a cavity within a plant cell enclosed by the cell walls
Derived Forms
lumenal, luminal, adjective
Word Origin
C19: New Latin, from Latin: light, aperture
Word Origin and History for lumen
n.

unit of luminosity, 1897, coined 1894 by French physicist André-Eugène Blondel (1863-1938) from Latin lumen "light," related to lucere "to shine" (see light (n.)).

lumen in Medicine

lumen lu·men (lōō'mən)
n. pl. lumens or lu·mi·na (-mə-nə)

  1. The inner open space or cavity of a tubular organ, as of a blood vessel.

  2. The unit of luminous flux in the International System of Units, that is equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions.

lu'men·al or lu'min·al adj.
lumen in Science
lumen
  (l'mən)   
Plural lumens or lumina

  1. The central space within a tube-shaped body part or organ, such as a blood vessel or the intestine.

  2. The SI derived unit used to measure the amount of light passing through a given area per second. One lumen is equal to the luminous flux passing per unit solid angle from a light source with a strength of one candela.