'pesticide-free' originates from modern English, formed by the compound of 'pesticide' and 'free'. 'Pesticide' itself comes from New Latin elements: 'pestis' (meaning 'pest' or 'plague') combined with the suffix '-cide' (from Latin 'caedere', 'to kill'), meaning 'a substance that kills pests'. 'Free' comes from Old English 'frēo', meaning 'not in bondage' and later 'without'.

'pesticide' developed in the 19th–20th century as a coined scientific term from New Latin roots ('pestis' + '-cide'), while 'free' goes back to Old English 'frēo' and Middle English forms; the modern compound 'pesticide-free' arose in contemporary English by combining the noun 'pesticide' with the adjective 'free' to indicate absence of pesticides.

Initially, 'free' primarily meant 'not in bondage' or 'exempt', but its use expanded to mean 'without' or 'not containing' (as in 'sugar-free'); thus 'pesticide-free' now means 'without pesticides'.