melancholia

From Late Latin melancholia, which was in turn borrowed from the Ancient Greek medical term μελαγχολία (melankholía, “blackness of the bile”) (from μέλας (mélas), μελαν- (melan-, “black, dark, murky”) + χολή (kholḗ, “bile”)), referring to the humour which ancient Hippocratic and later Galenic medicine associated with sadness and despondency. Doublet of melancholy.

来源：wiktionary