Main Entry: lu·mi·nos·i·ty

Pronunciation: \ˌlü-mə-ˈnä-sə-tē\

Function: noun

Inflected Form(s): plural lu·mi·nos·i·ties

Date: 1634

1 a : the quality or state of being luminous b : something luminous
2 a : the relative quantity of light b : relative brightness of something
3 : the relative quantity of radiation emitted by a celestial source (as a star)