'antimalaria' originates from Modern English, formed from the prefix 'anti-' (from Greek 'anti') meaning 'against' and 'malaria' (from Italian 'mal' + 'aria') meaning 'bad air'.

'malaria' entered English from Italian 'malaria' (literally 'bad air'), itself from Medieval Latin and Old Italian components 'mal' ('bad') + 'aria' ('air'); the prefix 'anti-' comes from Greek 'anti-' meaning 'against'. The combination produced the Modern English formation 'antimalaria' and related adjective 'antimalarial'.

Initially, 'malaria' referred to 'bad air' thought to cause the disease; over time it came to denote the disease itself. 'Antimalaria' therefore evolved from the literal 'against bad air' idea to mean 'against malaria' (i.e., measures or drugs that prevent or treat the disease).