'maltreat' originates from Latin via Old French, specifically the prefix 'mal-' from Latin 'malus' meaning 'bad' and the verb element from Old French 'traiter' (from Latin 'tractare') meaning 'to handle or deal with'.

'maltreat' changed from Old French 'maltraiter' and Middle English forms (e.g. 'maltreten') and eventually became the modern English word 'maltreat'.

Initially, it meant 'to deal with badly' (literally 'badly handle'), and over time it has kept the core sense of treating someone badly or abusively.