'dropsy' ultimately originates from Greek, specifically the word 'hydrops' (Greek 'hudrōps'), where 'hydor' meant 'water' and 'hudrōps' referred to a watery swelling (fluid accumulation).

'hydrops' passed into Late Latin/Medieval Latin as 'hydropsia' and then into Middle English as 'dropsie'/'dropsy'; the modern English 'dropsy' developed from these forms, and the colloquial plural/variant 'dropsies' arose later in informal speech to mean repeated dropping or clumsiness.

Initially it meant 'a watery swelling' (what we now call edema); over time the medical sense persisted in 'dropsy' while the playful colloquial form 'dropsies' evolved to mean 'the act or tendency of dropping things.'