The Collaborative International Dictionary of English v.0.48:

Integration \In`te*gra"tion\ ([i^]n`t[-e]*gr[=a]"sh[u^]n), n.
   [L. integratio a renewing, restoring: cf. F. int['e]gration.]
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   1. The act or process of making whole or entire.
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   2. (Math.) The operation of finding the primitive function
      which has a given function for its differential
      coefficient. See Integral.
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   Note: The symbol of integration is [integral2l] (standing for
         the Latin summa sum), and the integral is also regarded
         as the limiting value of the sum of great numbers of
         differentials, when the magnitude of the differentials
         decreases, and their number increases indefinitely. See
         Limit, n. When the summation is made between
         specified values of the variable, the result is a
         definite integral, and those values of the variable
         are the limits of the integral. When the summation is
         made successively for two or more variables, the result
         is a multiple integral.
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   3. In the theory of evolution: The process by which the
      manifold is compacted into the relatively simple and
      permanent. It is supposed to alternate with
      differentiation as an agent in development.
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WordNet (r) 3.0 (2006):

definite integral
    n 1: the integral of a function over a definite interval