chalk

noun

1
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
2
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
3
a pure flat white with little reflectance
4
a soft whitish calcite

Also useful for “chalk”:Wordle Solver— Five letters — perfect Wordle material