'nonarthropod' is a compound formed from the negative prefix 'non-' (from Latin 'non', meaning 'not') and 'arthropod' (from Greek roots 'arthron' meaning 'joint' and 'pous' meaning 'foot').

'arthropod' entered scientific vocabulary via New Latin 'Arthropoda' in the 19th century, derived from Greek 'arthron' + 'pous'; the English productive prefix 'non-' (from Latin 'non') has long been used to form negating compounds, and 'nonarthropod' is a modern English compound combining these elements.

The compound's meaning has been straightforward and literal since formation: it denotes something 'not an arthropod'; it has not undergone significant semantic shift.