'ill-treat' originates from Middle English, combining 'ill' meaning 'badly' and 'treat' from Old French 'traitier', meaning 'to handle or deal with'.

'ill-treat' evolved from the Middle English phrase 'ill trete', eventually becoming the modern English 'ill-treat'.

Initially, it meant 'to handle badly', but over time it evolved into its current meaning of 'to treat cruelly or unkindly'.