Emily Dickinson Lexicon

MEL'AN-CHOL-Y, n. [Gr. μελαν, black, and χολη, bile; L. melancholia.]

1. A gloomy state of mind, often a gloomy state that is of some continuance, or habitual; depression of spirits induced by grief; dejection of spirits. This was formerly supposed to proceed from a redundance of black bile. Melancholy, when extreme and of long continuance, is a disease, sometimes accompanied with partial insanity. Cullen defines it, partial insanity without dyspepsy.
2. In nosology, mental alienation restrained to a single object or train of ideas, in distinction from mania, in which the alienation is general. – Good. Moon-struck madness, moping melancholy. – Milton.