'monstrous' originates from Latin, specifically the word 'monstruosus,' where 'monstrum' meant 'monster.'

'monstruosus' transformed into the Old French word 'monstrueux,' and eventually became the modern English word 'monstrous.'

Initially, it meant 'pertaining to a monster,' but over time it evolved into its current meanings of 'extremely large or ugly' and 'shockingly wrong or unfair.'