'non-anatomical' is formed by prefixing 'non-' (from Latin 'non', meaning 'not') to 'anatomical', which ultimately comes from Greek 'anatomē' meaning 'dissection'.

'anatomical' came into English via Latin 'anatomia' and Old French, from Greek 'anatome' (ἀνατομή). The negative prefix 'non-' has been used in English since Middle English, adopted from Latin usage. The compound 'non-anatomical' is a modern English formation combining these elements.

Originally 'anatomical' referred specifically to dissection and the study of bodily structure; over time it broadened to mean anything relating to bodily structure, and 'non-anatomical' simply negates that relation (i.e., 'not relating to bodily structure').