lumen

[ loo-muhn ]

noun

, plural lu·mens, lu·mi·na [loo, -m, uh, -n, uh].

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. : lm
2. Anatomy. the canal, duct, or cavity of a tubular organ.
3. Botany. (of a cell) the cavity that the cell walls enclose.

lumen

/ ˈluːmɪn /

noun

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

lumen

/ lo̅o̅′mən /

, Plural lumens

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.

Derived Forms

• ˈlumenal, adjective

Word History and Origins

Origin of lumen¹

1870–75; < New Latin, special uses of Latin lūmen (stem lūmin- ) light, window

Word History and Origins

Origin of lumen¹

C19: New Latin, from Latin: light, aperture

Example Sentences

That’s why it’s best to look at the lumens instead of the wattage.

From Popular-Science

Besides lumens, the biggest factor for finding the best floodlight is position.

From Popular-Science

The number of lumens needed for an outdoor floodlight is between 700 and 2,5000.

From Popular-Science

Be sure to pay attention to the lumens or wattage of a light fixture – no dimly lit spaces here.

From Washington Blade

For huge spacesA junk-drawer flashlight’s brightness measures in the hundreds of lumens.

From Popular-Science

That reminds me, I'd better arrange a debate on immigration for the Lumen.

From Project Gutenberg

"She made a splendid impression on the Lumen," Colburn went on.

From Project Gutenberg

In the second main variety of gland the secretory portion is enlarged and the lumen variously increased in size.

From Project Gutenberg

At about the time when a lumen appears in the Oviduct the first traces of the Wolffian duct become visible.

From Project Gutenberg

While undergoing this change of position it also acquires a lumen, but ends blindly both in front and behind.

From Project Gutenberg