integral calculus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The study of integration and its uses, such as in finding volumes, areas, and solutions of differential equations.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun calculus The calculus that generalizes summation to find areas, masses, volumes, sums, and totals of quantities described by continuously varying functions.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the part of calculus that deals with integration and its application in the solution of differential equations and in determining areas or volumes etc.