Emily Dickinson Lexicon

TAR-TAR, n.¹ [Fr. tartre; Sp. tartaro; from tart, acid.]

1. An acid concrete salt, deposited from wines completely fermented, and adhering to the sides of the casks in the form of a hard crust. It is white or red, the white being most esteemed. In its crude state, it is much used as a flux in the assaying of ores. Nicholson. Cyc. The tartar of wine is a bitartrate of potassa, i. e. common cream of tartar.
2. A person of a keen irritable temper.
3. A native of Tartary; a corruption of Tatar.