A soft, earthy substance, of a white, grayish, or yellowish white color, consisting of calcium carbonate, and having the same composition as common limestone.
- A soft compact calcite, CaCO3, with varying amounts of silica, quartz, feldspar, or other mineral impurities, generally gray-white or yellow-white and derived chiefly from fossil seashells.
- A piece of chalk or chalklike substance in crayon form, used for marking on a blackboard or other surface.
- Games A small cube of chalk used in rubbing the tip of a billiard or pool cue to increase its friction with the cue ball.
- A mark made with chalk.
- Chiefly British A score or tally.
- To mark, draw, or write with chalk: chalked my name on the blackboard.
- To rub or cover with chalk, as the tip of a billiard cue.
- To make pale; whiten.
- To treat (soil, for example) with chalk.
- chalk up To earn or score: chalk up points.
- chalk up To credit or ascribe: Chalk that up to experience.