n.
Pronunciation: ' tär-t ə r
Function: noun
Etymology: Middle English, from Anglo-French, from Medieval Latin tartarum
Date: 14th century
1 : a substance consisting essentially of cream of tartar that is derived from the juice of grapes and deposited in wine casks together with yeast and other suspended matters as a pale or dark reddish crust or sediment especially : a recrystallized product yielding cream of tartar on further purification
2 : an incrustation on the teeth consisting of plaque that has become hardened by the deposition of mineral salts (as calcium carbonate)