- chalkA soft, white, powdery limestone (calcium carbonate, CaCO₃).
- chalicosisA form of pneumoconiosis affecting the lungs or bronchioles, found chiefly among stonecutters.
- chalicothereAny of various odd-toed ungulates of the family Chalicotheriidae, from the Eocene and Pleistocene periods, which had horse-like heads and apelike bodies.