1. 牙垢;牙石
    Tartar is a hard yellowish substance that forms on your teeth and causes them to decay if it is not removed.

2. 凶悍的人，脾气暴戾的人;(尤指)悍妇
    If you describe someone, especially a woman in a position of authority, as a tartar, you mean that they are fierce, bad-tempered, and strict.

    e.g. She can be quite a tartar.
           她有时真是个悍妇。

3. see also: cream of tartar

1. an incrustation that forms on the teeth and gums

    Synonym: calculustophus

2. a fiercely vigilant and unpleasant woman

    Synonym: dragon

3. a salt used especially in baking powder

    Synonym: cream of tartarpotassium bitartratepotassium hydrogen tartrate