Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
 noun Medicine An abnormal concretion in the body, usually formed of mineral salts and found in the gallbladder, kidney, or urinary bladder, for example.
 noun The branch of mathematics that deals with limits and the differentiation and integration of functions of one or more variables.
 noun A method of analysis or calculation using a special symbolic notation.
 noun The combined mathematics of differential calculus and integral calculus.
 noun A system or method of calculation.
from The Century Dictionary.
 noun A small stone; a pebble.
 noun In pathology, a general term for inorganic concretions of various kinds formed in various parts of the body.
 noun In mathematics, any highly systematic method of treating a large variety of problems by the use of some peculiar system of algebraic notation.
from the GNU version of the Collaborative International Dictionary of English.
 noun (Med.) 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
 noun (Math.) A method of computation; any process of reasoning by the use of symbols; any branch of mathematics that may involve calculation.
 noun a method of treating geometry by defining a point as the center of gravity of certain other points to which coëfficients or weights are ascribed.
 noun that branch of mathematics which treats of the forms of functions that shall satisfy given conditions.
 noun that branch of mathematical logic that treats of all operations that satisfy given conditions.
 noun the science that treats of the computation of the probabilities of events, or the application of numbers to chance.
 noun a branch of mathematics in which the laws of dependence which bind the variable quantities together are themselves subject to change.
 noun a method of investigating mathematical questions by using the ratio of certain indefinitely small quantities called
differentials . The problems are primarily of this form: to find how the change in some variable quantity alters at each instant the value of a quantity dependent upon it.  noun that part of algebra which treats of exponents.
 noun a method of investigating the relations of real or imaginary quantities by the use of the imaginary symbols and quantities of algebra.
 noun a method which in the reverse of the differential, the primary object of which is to learn from the known ratio of the indefinitely small changes of two or more magnitudes, the relation of the magnitudes themselves, or, in other words, from having the differential of an algebraic expression to find the expression itself.
from Wiktionary, Creative Commons Attribution/ShareAlike License.
 noun dated, countable
calculation ,computation  noun countable, mathematics Any formal system in which
symbolic expressions are manipulated according to fixed rules.  noun uncountable, mathematics
Differential calculus andintegral calculus considered as a single subject;analysis .  noun countable, medicine A stony
concretion that forms in a bodily organ.  noun uncountable, dentistry Deposits of
calcium phosphate salts on teeth.  noun countable A decisionmaking method, especially one appropriate for a specialised realm.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
 noun the branch of mathematics that is concerned with limits and with the differentiation and integration of functions
 noun a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body
 noun an incrustation that forms on the teeth and gums
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
from Wiktionary, Creative Commons Attribution/ShareAlike License
Examples

Be it women, money, power or fame, the calculus is the same. drkrick says:

For the GOPer base, the calculus is the following: Tax money spent on infrastructure, running the gov't and and foreign and domestic programs?

So Midland, plainly put, you think we should spend money on killing people for the political benefit of the Democratic party, and that anyone who objects to this calculus is a petulant child?

So Midland, plainly put, you think we should spend money on killing people for the political benefit of the Democratic party, and that anyone who objects to this calculus is a petulant child?

For the GOPer base, the calculus is the following:

So Midland, plainly put, you think we should spend money on killing people for the political benefit of the Democratic party, and that anyone who objects to this calculus is a petulant child?

I'm sure they'll regret putting the world's drug industry out of business, but the political calculus is pretty clear.
Quack Remedy, Arnold Kling  EconLog  Library of Economics and Liberty

I went from getting As in calculus to getting B minuses and Cs. I just couldn't concentrate.

The Governor's political calculus is clear: It is better to leave public services in tatters than impose higher taxes on corporations reaping record profits in the midst of the Great Recession.
Elissa D. Barrett: To the Righteous, Wealth Is a Greater Test Than Poverty

Another thing about calculus is that I didn't actually retain a lot of the information.
Steven Levitt, Arnold Kling  EconLog  Library of Economics and Liberty
jennarenn commented on the word calculus
Having taken calculus in both high school and college, I think that standard curriculum really doesn't appeal to the kinesthetic modality. A life goal of mine is to write the new classic, Calculus for the Kinesthetic Learner. Actually understanding the stuff is an intermediate goal that I keep putting off. ;)
August 10, 2007
uselessness commented on the word calculus
I'm still waiting for Life for the Kinesthetic Learner.
August 10, 2007
jennarenn commented on the word calculus
I'll get right to work. ;)
August 11, 2007