English
lux
Lux comes from Latin lūx ‘light’, and goes back to Proto-Indo-European *lewk- ‘white’.
- Proto-Indo-Europeanc. 4500–2500 BCE*lewk-1‘white’reconstructed
- Proto-Indo-Europeanc. 4500–2500 BCE*léwks2reconstructed
- Proto-Italicc. 1500–700 BCE*louks2reconstructed
- Latinc. 75 BCE–200 CElūx1‘light’
- Englishearliest quotation 2025lux1
attested reconstructed ? uncertain or disputed deepest recorded ancestor
- 1 Wiktionary, English lux
- 2 Wiktionary, Latin lux
- Earliest quotation in Wiktionary’s entry: 2025, Veronique Greenwood, Your Bedroom Probably Isn't Dark Enough: “Some volunteers slept in ambient light of about 100…”.
Lineage
- Proto-Indo-Europeanc. 4500–2500 BCE*lewk-Wiktionary, English lux‘white’reconstructed
- Proto-Indo-Europeanc. 4500–2500 BCE*léwksWiktionary, Latin luxreconstructed
- Proto-Italicc. 1500–700 BCE*louksWiktionary, Latin luxreconstructed
- Latinc. 75 BCE–200 CElūxWiktionary, English lux‘light’
- Englishearliest quotation 2025luxWiktionary, English lux. Earliest quotation in Wiktionary’s entry: 2025, Veronique Greenwood, Your Bedroom Probably Isn't Dark Enough: “Some volunteers slept in ambient light of about 100…”
Linked words
through Proto-Indo-European *lewk- ‘white’
light, low, link, los, ounce, lea, lunar, illumination, luna, illuminate, lynx, translucent, luminous, lucid, lumen, luminosity, lucerne, lumia, leucine, luminescent, lucent, luminary, lune, lum, luminal, 72 more
through Proto-Indo-European *léwks
through Latin lūx ‘light’
Today it means
noun In the International System of Units, the derived unit of illuminance or illumination; one lumen per square metre. Symbol: lx
Sources
Sources: Wiktionary, “lux”; the older steps come from the Wiktionary entry for Latin lux. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.
Etymograph / Proto-Indo-European *lewk- / lux