'simple-leaved' is formed from the adjective 'simple' + noun 'leaf' with the adjectival suffix '-ed'. 'simple' originates from Latin, specifically the word 'simplex', where 'simplex' meant 'single' or 'undivided'; 'leaf' originates from Old English 'lēaf' (also written 'lǣf').

'simple' passed into English via Old French and Middle English from Latin 'simplex'; 'leaf' comes from Old English 'lēaf' and developed into Middle English 'leaf' and modern English 'leaf'. The compound adjective 'simple-leaved' is a modern English formation combining these elements with '-ed'.

Initially the elements meant 'single' (simplex) and 'leaf' (lēaf); combined as 'simple-leaved' the meaning — having a single, undivided leaf blade — has remained stable in botanical usage.