calculus

n. method of mathematical computation; abnormal mineral buildup in the body; gravel; small cup-like structure (Anatomy); system composed of many complex parts

Calculus (Latin, calculus, a small stone used for counting) is a branch of mathematics that includes the study of limits, derivatives, integrals, and infinite series, and constitutes a major part of modern university education. Historically, it was sometimes referred to as "the calculus", but that usage is seldom seen today. Calculus has widespread applications in science and engineering and is used to solve complicated problems for which algebra alone is insufficient. Calculus builds on algebra, trigonometry, and analytic geometry and includes two major branches, differential calculus and integral calculus, that are related by the fundamental theorem of calculus. In more advanced mathematics, calculus is usually called analysis and is defined as the study of functions.
See more at Wikipedia.org...

Calculus /cal·cu·lus/ pl. cal´culi [L.] an abnormal concretion, usually composed of mineral salts, occurring within the animal body. [more]Calculus - Community and Resources

Noun
1. 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"
(synonym) concretion
(hypernym) rock, stone
(hyponym) bladder stone, cystolith
2. an incrustation that forms on the teeth and gums
(synonym) tartar, tophus
(hypernym) crust, incrustation, encrustation
3. the branch of mathematics that is concerned with limits and with the differentiation and integration of functions
(synonym) the calculus, infinitesimal calculus
(hypernym) pure mathematics
(hyponym) analysis
(derivation) calculate, cipher, cypher, compute, work out, reckon, figure
(classification) mathematics, math, maths

(n.)
Any solid concretion, formed in any part of the body, but most frequent in the organs that act as reservoirs, and in the passages connected with them; as, biliary calculi; urinary calculi, etc.
  

(n.)
A method of computation; any process of reasoning by the use of symbols; any branch of mathematics that may involve calculation.