lumen
UK[ˈluːmən]US[ˈluːmən]
n
the si unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time.
n
(anatomy) the cavity or channel within a tube or tubular organ, such as a blood vessel or intestine.
Etymology
the word 'lumen' was borrowed directly from latin, where it means "light, an opening for light, or the eye." it is derived from the proto-indo-european root lewk-, meaning "light, brightness." this root is the source of many light-related words across indo-european languages, such as 'lux' (light) in latin, 'leukos' (white, bright) in greek, and 'light' in english. in scientific terminology, the term was adopted in physics to denote a unit of luminous flux, drawing directly on its core meaning of "light," and in anatomy to describe a channel or opening, preserving its secondary latin sense of "an opening through which light passes."
Analysis
the word is a direct latin loanword used as a simplex unit in english.
Examples
a standard 100-watt incandescent bulb emits roughly 1600 lumens of light.
the surgeon carefully cleared the blocked lumen of the artery.
the new led lamp provides excellent illumination with a high lumen output per watt.