early 15c., "full of light, shiny," from Latin luminosus "shining, full of light, conspicuous," from lumen (genitive luminis) "light," from suffixed form of PIE root *leuk- "light, brightness." Related: Luminously; luminousness.
a sky luminous with stars
luminary
luminate
luminescence
luminescent
luminosity
luminous
lummox
lump
lumpectomy
lumpenproletariat
lumpish