'scent-free' originates from Modern English as a compound of 'scent' and 'free'; 'scent' ultimately comes from Old French (from Latin 'sentire'), where the root meant 'to perceive (by the senses)', and 'free' comes from Old English 'frēo', where 'frēo' meant 'not in bondage, free.'

'scent' developed from Latin 'sentire' → Old French 'sentir' (noun/verb forms related to smell/perception) → Middle English 'scent' (sense of smell); 'free' traces from Old English 'frēo' → Middle English 'free'; the compound 'scent-free' formed in Modern English by combining the noun 'scent' with the adjective 'free' to mean 'free from scent.'

Initially the parts referred to 'sense/perception of smell' ('scent') and 'not restricted' ('free'); together they evolved into the compound meaning 'without scent' or 'unscented.'