Calculus

noun

1. Calculation; computation.
2. Any formal system in which symbolic expressions are manipulated according to fixed rules.

   "lambda calculus"

3. (often definite, the calculus) Differential calculus and integral calculus considered as a single subject; analysis.
4. A stony concretion that forms in a bodily organ.

   "renal calculus ( = kidney stone)"

5. Deposits of calcium phosphate salts on teeth.