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

The Collaborative International Dictionary of English v.0.48:

Integral \In"te*gral\, a. [Cf. F. int['e]gral. See Integer.] [1913 Webster] 1. Lacking nothing of completeness; complete; perfect; uninjured; whole; entire. [1913 Webster] A local motion keepeth bodies integral. --Bacon. [1913 Webster] 2. Essential to completeness; constituent, as a part; pertaining to, or serving to form, an integer; integrant. [1913 Webster] Ceasing to do evil, and doing good, are the two great integral parts that complete this duty. --South. [1913 Webster] 3. (Math.) (a) Of, pertaining to, or being, a whole number or undivided quantity; not fractional. (b) Pertaining to, or proceeding by, integration; as, the integral calculus. [1913 Webster] Integral calculus. See under Calculus. [1913 Webster]The Collaborative International Dictionary of English v.0.48:

Calculus \Cal"cu*lus\, n.; pl. Calculi. [L, calculus. See Calculate, and Calcule.] 1. (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; as, biliary calculi; urinary calculi, etc. [1913 Webster] 2. (Math.) A method of computation; any process of reasoning by the use of symbols; any branch of mathematics that may involve calculation. [1913 Webster] Barycentric calculus, a method of treating geometry by defining a point as the center of gravity of certain other points to which co["e]fficients or weights are ascribed. Calculus of functions, that branch of mathematics which treats of the forms of functions that shall satisfy given conditions. Calculus of operations, that branch of mathematical logic that treats of all operations that satisfy given conditions. Calculus of probabilities, the science that treats of the computation of the probabilities of events, or the application of numbers to chance. Calculus of variations, a branch of mathematics in which the laws of dependence which bind the variable quantities together are themselves subject to change. Differential calculus, 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. Exponential calculus, that part of algebra which treats of exponents. Imaginary calculus, a method of investigating the relations of real or imaginary quantities by the use of the imaginary symbols and quantities of algebra. Integral calculus, 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. [1913 Webster]WordNet (r) 3.0 (2006):

integral calculus n 1: the part of calculus that deals with integration and its application in the solution of differential equations and in determining areas or volumes etc.