melancholia
Melancholia (noun) means a deep and lasting feeling of sadness or gloom.
Etymology
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.