'antiparasitic' originates from a modern English formation combining the prefix 'anti-' (from Greek 'anti' meaning 'against') and 'parasitic' (from Greek/Latin roots related to 'parasite').

'parasitic' comes from Greek 'parasitos' (παράσιτος), through Late Latin 'parasiticus' and Old French/Medieval Latin influences, and 'anti-' is from Greek 'anti-'; these elements combined in modern English to form 'antiparasitic', with the adverbial suffix '-ally' producing 'antiparasitically'.

Initially, the roots referred to a 'person who eats at another's table' (Greek 'parasitos'), but over time 'parasitic' became associated with organisms that live off hosts; 'antiparasitic' then came to mean 'against parasites', and 'antiparasitically' means 'in a way that opposes or treats parasites'.