Definition of tartar:

part of speech: noun

An inhabitant or native of Tartary; one who proves too strong or cunning for his assailant, as in the phrase, " to catch a Tartar".

part of speech: noun

The white or reddish acid substance which gathers on the sides of casks and vats containing wine, in the form of a hard crust, and frequently as a white crust on the teeth.