Old English glæm "a brilliant light; brightness; splendor, radiance, beauty," from Proto-Germanic *glaimiz (cognates: Old Saxon glimo "brightness;" Middle High German glim "spark," gleime "glow-worm;" German glimmen "to glimmer, glow;" Old Norse glja "to shine, glitter, glisten"), from root *glim-, from PIE *ghel- (2) "to shine," with derivatives referring to bright materials and gold (see glass, n., and compare glad, adj.).

early 13c., from gleam (n). Related: Gleamed; gleaming.