late 13c., "to shine brightly," from or related to Middle Dutch, Middle Low German glaren "to gleam," from Proto-Germanic *glaz-, from PIE root *ghel- (2) "to shine." Sense of "stare fiercely" is from late 14c. Related: Glared; glaring.
c. 1400, "bright light, dazzling glitter," from glare (v.); especially in reference to light reflected off some surface (17c.). From 1660s in sense of "fierce look." Old English glær (n.) meant "amber."
The girl glared at the man who tried to make a pass at her
The moon glared back at itself from the lake's surface
The sun glared down on us
a glare of sunlight
when Congress investigates it brings the full glare of publicity to the agency