definition of
calculus

[1] #1 calculus n. [concretion] a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body; "renal calculi can be very painful". wn

[2] #2 calculus n. [tartar, tophus] an incrustation that forms on the teeth and gums. wn

[3] #3 calculus n. [infinitesimal calculus] the branch of mathematics that is concerned with limits and with the differentiation and integration of functions. wn