'equal-footed' originates from Modern English, specifically the compound of 'equal' and 'footed', where 'equal' ultimately comes from Latin 'aequalis' meaning 'even/level' and 'footed' comes from Old English 'fōt' meaning 'foot'.

'equal' changed from Old French 'equel' (from Latin 'aequalis'), and 'footed' derives from Old English 'fōt' with the adjectival suffix '-ed'; these elements combined in English to form the compound 'equal-footed'.

Initially the components meant 'even/level' (from 'aequalis') and 'foot' (from Old English), but over time the compound came to mean 'having equal standing' or 'being on equal terms'.