mid-14c., "to shine;" c. 1500, "to stare with wide eyes," perhaps from a Scandinavian source (compare Norwegian dialectal glora "to glow, gleam; stare"), or related to Middle Dutch gluren "to leer;" in either case from Proto-Germanic *glo- (see glow (v.)), root of Old English glowan "to glow," which influenced the spelling of this word. Meaning "to look angrily, look intently and threateningly, scowl" is from 18c. Related: Glowered; glowering. As a noun, 1715, "an angry or threatening stare," from the verb.
Entries linking to glower
Proto-Indo-European root meaning "to shine;" it forms words for "gold" (the "bright" metal), words denoting colors, especially "yellow" and "green," also "bile, gall," for its color, and a large group of Germanic gl- words having to do with shining and glittering and, perhaps, sliding. Buck says the interchange of words for yellow and green is "perhaps because they were applied to vegetation like grass, cereals, etc., which changed from green to yellow."
It forms all or part of: arsenic; Chloe; chloral; chloride; chlorinate; chlorine; chloro-; chloroform; chlorophyll; chloroplast; cholecyst; choler; cholera; choleric; cholesterol; cholinergic; Cloris; gall (n.1) "bile, liver secretion;" gild; glad; glance; glare; glass; glaze; glazier; gleam; glee; glib; glide; glimmer; glimpse; glint; glissade; glisten; glister; glitch; glitter; glitzy; gloaming; gloat; gloss (n.1) "glistening smoothness, luster;" glow; glower; gold; guilder; jaundice; melancholic; melancholy; yellow; zloty.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit harih "yellow, tawny yellow," hiranyam "gold;" Avestan zari "yellow;" Old Persian daraniya-, Avestan zaranya- "gold;" Greek khlōros "greenish-yellow color," kholos "bile, gall, wrath;" Latin helvus "yellowish, bay," Gallo-Latin gilvus "light bay;" Lithuanian geltonas "yellow;" Old Church Slavonic zlutu, Polish żółty, Russian zeltyj "yellow;" Latin galbus "greenish-yellow," fellis "bile, gall;" Lithuanian žalias "green," želvas "greenish," tulžis "bile;" Old Church Slavonic zelenu, Polish zielony, Russian zelenyj "green;" Old Irish glass, Welsh and Breton glas "green," also "gray, blue;" Old English galla "gall, bile," geolu, geolwe, German gelb, Old Norse gulr "yellow;" Old Church Slavonic zlato, Russian zoloto, Old English gold, Gothic gulþ "gold;" Old English glæs "glass; a glass vessel."
1570s, "to look at furtively," probably a variant of earlier glout "to gaze attentively, stare, scowl, look glum, pout" (mid-15c.), from a Scandinavian source such as Old Norse glotta "to grin, smile scornfully and show the teeth," Swedish dialectal glotta "to peep;" or from Middle High German glotzen "to stare, gape," from the Germanic group of *gl- words that also includes glower, from PIE root *ghel- (2) "to shine." Sense of "to look at with malicious satisfaction, ponder with pleasure something that satisfies an evil passion" first recorded 1748. Johnson didn't recognize the word, and OED writes that it was probably "taken up in the 16th c. from some dialect." Related: Gloated; gloating. As a noun, from 1640s with sense of "side-glance;" 1899 as "act of gloating."
Whosoever attempteth anything for the publike ... the same setteth himselfe upon a stage to be glouted upon by every evil eye. [translators' "note to the reader" in the 1611 King James Bible]