'demean' originates from Old French, specifically the word 'demeener', where 'de-' meant 'completely' (or intensive) and 'meener' meant 'to lead' or 'to conduct'.

'demean' changed from Middle English 'demenen' (borrowed from Old French 'demeener') and eventually became the modern English word 'demean'.

Initially, it meant 'to conduct or manage (oneself)', but over time it evolved to include the sense 'to lower in dignity or humiliate' while retaining the older meaning of 'behave' in some contexts.