'nonimmune' originates from Latin elements: the prefix 'non-' (from Latin 'non') meaning 'not', combined with 'immune' from Latin 'immunis' meaning 'exempt'.

'nonimmune' developed in modern English by attaching the negative prefix 'non-' to the adjective 'immune'. 'Immune' came into English via Old French 'immune' from Latin 'immunis', and the compound form 'non-immune' appears later in modern usage.

Originally Latin 'immunis' meant 'exempt' (for example, exempt from public duty or tax); over time 'immune' shifted toward the idea of being protected from disease, and 'nonimmune' now denotes 'not protected' or 'lacking immunity'.