noun A soft, white, powdery limestone (calcium carbonate, CaCO3).
chalk cliffs are not recommended for climbing
noun A piece of chalk, or nowadays processed compressed gypsum (calcium sulfate, CaSO4), that is used for drawing and for writing on a blackboard (chalkboard).
noun Tailor's chalk.
noun A white powdery substance used to prevent hands slipping from holds when climbing, or losing grip in weight-lifting or gymnastics, sometimes but not always limestone-chalk, often magnesium carbonate (MgCO3).
when working out your next move, it's a good idea to get some more chalk from the bag
noun A platoon-sized group of airborne soldiers.
noun The favorite in a sporting event.
noun The prediction that there will be no upsets, and the favored competitor will win.
verb To apply chalk to anything, such as the tip of a billiard cue.