Source : Webster's Revised Unabridged Dictionary (1913)

Metabolism \Me*tab"o*lism\, n. (Physiol.)
   The act or process, by which living tissues or cells take up
   and convert into their own proper substance the nutritive
   material brought to them by the blood, or by which they
   transform their cell protoplasm into simpler substances,
   which are fitted either for excretion or for some special
   purpose, as in the manufacture of the digestive ferments.
   Hence, metabolism may be either constructive ({anabolism}),
   or destructive ({katabolism}).

Metabolism \Me*tab"o*lism\, n. (Biol.)
   The series of chemical changes which take place in an
   organism, by means of which food is manufactured and utilized
   and waste materials are eliminated.

Source : WordNet®

metabolism
     n 1: the marked and rapid transformation of a larva into an adult
          that occurs in some animals [syn: {metamorphosis}]
     2: the organic processes (in a cell or organism) that are
        necessary for life [syn: {metabolic process}, {metastasis}]