n.1 a hard deposit of saliva, calcium phosphate, etc., that forms on the teeth.
2 a deposit of acid potassium tartrate that forms a hard crust on the inside of a cask during the fermentation of wine.
Phrases and idioms:
tartar emetic potassium antimony tartrate used as a mordant and in medicine (formerly as an emetic).
Derivatives:
tartarize v.tr. (also -ise).
Etymology: ME f. med.L f. med.Gk tartaron