brightness
n. uncountablen. the amount of light that something gives out or reflects. It can also describe how smart or cheerful someone is.
n. the quality or state of being luminous or reflecting light. Often used figuratively to describe intelligence or a cheerful disposition.
You can adjust the brightness of your phone screen in the settings.
The sudden brightness of the morning sun made him squint as he stepped outside.
Astronomers measure the absolute brightness of stars to determine their distance from Earth, accounting for the atmospheric interference that can dim their appearance to the naked eye.
From Middle English bryghtnes, brightnesse, from Old English beorhtnes (“brightness, splendor”), from Proto-West Germanic *berhtnassī, equivalent to bright + -ness. Cognate with Old High German berahtnessī, berahtnessi (“brightness”).
Uncountable when referring to the general quality of light; can be modified by adjectives like 'blinding' or 'dazzling'.