Noun

1. A soft whitish calcite
2. A pure flat white with little reflectance
3. An amphetamine derivative (trade name methedrine) used in the form of a crystalline hydrochloride; used as a stimulant to the nervous system and as an appetite suppressant
4. A piece of calcite or a similar substance, usually in the shape of a crayon, that is used to write or draw on blackboards or other flat surfaces

Verb

1. Write, draw, or trace with chalk