CALCULUS

noun (plural calculi; also -luses) Etymology: Latin, stone (used in reckoning) Date: 1666 1. a method of computation or calculation in a special notation (as of logic or symbolic logic), the mathematical methods comprising differential and integral ~, calculation , 3. a concretion usually of mineral salts around organic material found especially in hollow organs or ducts, tartar I,2, a system or arrangement of intricate or interrelated parts