A calculus is a mineral deposit resembling a stone at abnormal body locations. Plural: calculi. A kidney stone is called a renal calculus; stones in the salivary glands are called calculi of the salivary glands. The clinical condition of having calculi, however, is described by (medical name of organ)-lithiasis. For example: the condition of kidney stone: nephrolithiasis gallbladder stone: cholelithiasis stone in salivary glands: sialolithiasis