'glower' originates from Middle English, specifically the word 'glowren,' where 'glow-' meant 'to stare or look intently.'

'glowren' transformed into the modern English word 'glower,' and eventually became 'glowerer' to denote a person who glowers.

Initially, it meant 'to stare or look intently,' but over time it evolved into its current meaning of 'to look angrily or sullenly.'