'mixed-leaved' originates from Modern English as a compound of 'mixed' and 'leaved'. 'mixed' ultimately comes from Latin, specifically the word 'miscēre', where the root 'misc-' meant 'to mix'; 'leaved' derives from Old English 'lēaf', where 'lēaf' meant 'leaf'.

'mix' entered English via Old French (e.g. 'mescler' / 'mesclier') from Latin 'miscēre'; 'leaf' comes from Old English 'lēaf' and Middle English 'leaf'. The adjectival compound 'mixed-leaved' developed in Modern English by combining the past-participle form 'mixed' with the adjectival/past-participle form 'leaved'.

Initially the components meant 'mixed' (combined) and 'leaf' (foliage); over time the compound came to mean specifically 'having leaves of more than one form' rather than simply 'mixed' in a general sense.