Source : Webster's Revised Unabridged Dictionary (1913)

Assimilation \As*sim`i*la"tion\, n. [L. assimilatio: cf. F.
   assimilation.]
   1. The act or process of assimilating or bringing to a
      resemblance, likeness, or identity; also, the state of
      being so assimilated; as, the assimilation of one sound to
      another.

            To aspire to an assimilation with God. --Dr. H.
                                                  More.

            The assimilation of gases and vapors. --Sir J.
                                                  Herschel.

   2. (Physiol.) The conversion of nutriment into the fluid or
      solid substance of the body, by the processes of digestion
      and absorption, whether in plants or animals.

            Not conversing the body, not repairing it by
            assimilation, but preserving it by ventilation.
                                                  --Sir T.
                                                  Browne.

   Note: The term assimilation has been limited by some to the
         final process by which the nutritive matter of the
         blood is converted into the substance of the tissues
         and organs.

Source : WordNet®

assimilation
     n 1: the state of being assimilated; people of different
          backgrounds come to see themselves as part of a larger
          national family
     2: the social process of absorbing one cultural group into
        harmony with another [syn: {absorption}]
     3: the process of absorbing nutrients into the body after
        digestion [syn: {absorption}]
     4: a linguistic process by which a sound becomes similar to an
        adjacent sound
     5: the process of assimilating new ideas into an existing
        cognitive structure [syn: {acculturation}]
     6: in the theories of Jean Piaget: the application of a general
        schema to a particular instance