'hydrops' originates from Medieval Latin and Neo-Latin medical usage, ultimately from Greek 'ὕδρωψ' (hydrōps), where 'hydr-' (from ὕδωρ) meant 'water'.

'hydrops' passed into Late/Medieval Latin as 'hydrops' or 'hydropsia' from Greek 'ὕδρωψ'; it entered modern English via Latin medical terminology and Neo-Latin usage.

Initially it referred generally to a 'watery swelling' or 'dropsy'; over time it became a technical medical term for abnormal fluid accumulation (including specific uses such as 'hydrops fetalis').