'behave' originates from Middle English, specifically from the word 'behaven' (be- + have), where 'be-' was an intensifying or causative prefix and 'have' meant 'to have' or 'to hold'.

'behave' changed from Middle English 'behaven' and later shifted in form and spelling to the modern English 'behave'.

Initially, it meant 'to have or hold oneself' (roughly 'to carry oneself'); over time it evolved into the sense 'to conduct or bear oneself' and now commonly means 'to act' or 'to behave (in a particular way)'.