'antihydropic' originates from modern English, formed by combining the prefix 'anti-' (from Greek 'anti', meaning 'against') and 'hydropic' (from Greek root 'hydōr' meaning 'water' via medical Late Latin/Modern formation).

'hydropic' derives from the medical/Latin term 'hydrops' (from Greek 'hydōr' for 'water') used to denote dropsy or fluid accumulation; 'antihydropic' formed in modern English by prefixing 'anti-' to this medical adjective to indicate opposition to hydropic conditions.

Initially the components meant 'against' + 'water-related/dropsical condition'; the combined word has retained this sense, meaning 'opposing or preventing fluid accumulation (edema)'.