epidemy

From Middle English ipedemye, impedyme, from Middle French epydimie, epydemie, from Old French ypidime, from Late Latin epidemia, from Ancient Greek ἐπιδήμιος (epidḗmios), from ἐπί (epí, “upon”) + δῆμος (dêmos, “people”). Compare French épidémie.

来源：wiktionary