'non-natural' is formed from the prefix 'non-' (from Latin 'non', meaning 'not') and the adjective 'natural' (from Latin 'natura', meaning 'birth, nature').

'natural' passed from Latin 'natura' into Old French 'nature' and Middle English 'nature'/'natural', while the negative prefix 'non-' has been used in English since Middle English to form opposites; the compound 'non-natural' is a modern combination of these elements.

Initially the elements meant 'not' + 'of nature/born', and the compound has retained the basic sense of 'not of nature' or 'artificial', though specific usages have expanded to technical or legal contexts.