Lumen

How to spell lumen

5 letters · 2 syllables

How to pronounce lumen

Say the part in capitals loudest.

What does lumen mean?

1. nounThe SI unit of luminous flux, measuring the total visible light emitted by a source.
2. nounThe hollow inner cavity or channel of a tubular structure such as a blood vessel or the intestine.

Lumen in a sentence

• A lumen is the unit used to measure the light a bulb gives out.

• Plaque had narrowed the lumen of the artery considerably.

• The projector specification lists its peak output in lumen per channel.

• The surgeon inspected the lumen of the bowel for any blockage.

Where does lumen come from?

Language of origin: Latin

This word is borrowed directly and unchanged from the Latin lumen, which meant 'light' or 'a source of light', and by extension 'an opening' through which light could pass. The Latin noun is related to lux, the more familiar Latin word for 'light', and both trace back to an ancient root meaning 'to shine'. Scientists adopted lumen in the nineteenth and early twentieth centuries as a formal unit of luminous flux, keeping the original Latin spelling intact. Anatomists separately seized on the 'opening' sense to name the hollow channel inside a tube-shaped organ, such as a blood vessel or the intestine. Because the word was lifted straight from Latin rather than reshaped through French, it kept its clean spelling, and its plural in technical writing is often the Latin 'lumina'.

How the word is built

• lumen (Latin: light, opening)