Emily Dickinson Lexicon

DUMP, n. [from the root of dumb; D. dom; G. dumm.]

1. A dull gloomy state of the mind; sadness; melancholy; sorrow; heaviness of heart. In doleful dumps. – Gay.
2. Absence of mind; revery. – Locke.
3. A melancholy tune or air. – Shak. [This is not an elegant word, and in America, I believe, is always used in the plural; as, the woman is in the dumps.]