lumen
lumen Lexical Profile
lumen Game Scores & Validity
• noun
The standard SI unit of luminous flux, equal to the amount of visible light emitted per second in a unit solid angle of one steradian from a uniform source of one candela.
"This energy-efficient LED bulb produces 800 lumens of brightness while using only nine watts of power."
The central cavity or interior passageway of a tubular organ or anatomical structure, such as a blood vessel, intestine, or kidney tubule, or the internal space within a plant cell wall.
"The accumulation of cholesterol plaque along the arterial walls gradually narrowed the lumen of the blood vessel."
Word Nuance & Usage
In physics and everyday lighting, the plural is usually 'lumens', whereas in anatomy and biology, the Latinate plural 'lumina' is preferred. In consumer lighting, 'lumens' measure actual brightness (luminous flux), while 'watts' measure energy consumption.
• Rhymes for lumen
• Nearby Words
Word Origin & Etymology
Borrowed directly from Latin 'lumen', meaning 'light' or 'an opening for light', ultimately derived from the Proto-Indo-European root *leuk- ('light, brightness').