The verb glower, “to look or stare with sullen dislike” comes from Middle English gloren [or] glouren “to shine, gleam, glow, stare, stare at fixedly.” The Middle English forms are mostly from the north (Yorkshire) and Scotland. [T]he sense “to stare at fixedly” is Scottish. The source of gloren and glouren is obscure but, possibly, Scandinavian, e.g., Icelandic [as] glóra “to glow (like a cat’s eyes)” [or] Swedish and Norwegian dialect glora “to glow, stare.” The source of gloren [and] glouren may also be from Middle Low German glūren “to be overcast” or Dutch glueren “to leer, peep.” Glower entered English in the 15th century.
This is very similar to our “glaring at someone” which has its roots in Middle English, Middle Dutch and Middle Low German.
I’ve been doing a lot of glowering and glaring, lately. The whole world has gone insane-stupid. ~Vic