'behaviour' originates from Middle English, specifically the word 'behave,' where 'be-' meant 'thoroughly' and 'have' meant 'to hold or possess.'

'behave' changed from the Old French word 'behaivre' and eventually became the modern English word 'behaviour.'

Initially, it meant 'to conduct oneself,' but over time it evolved into its current meaning of 'the way in which one acts or conducts oneself.'