Source : Webster's Revised Unabridged Dictionary (1913)

Nutrition \Nu*tri"tion\, n. [Cf. F. nutrition. See
   {Nutritious}.]
   1. (Physiol.) In the broadest sense, a process or series of
      processes by which the living organism as a whole (or its
      component parts or organs) is maintained in its normal
      condition of life and growth.

   Note: In this wide sense it comprehends digestion,
         absorption, circulation, assimilation, etc., in fact
         all of the steps by which the nutritive matter of the
         food is fitted for incorporation with the different
         tissues, and the changes which it undergoes after its
         assimilation, prior to its excretion. See {Metabolism}.

   2. (Physiol.) In a more limited sense, the process by which
      the living tissues take up, from the blood, matters
      necessary either for their repair or for the performance
      of their healthy functions.

   3. That which nourishes; nutriment.

            Fixed like a plant, on his peculiar spot, To draw
            nutrition, propagate, and rot.        --Pope.

Source : WordNet®

nutrition
     n 1: (physiology) the organic process of nourishing or being
          nourished; the processes by which an organism
          assimilates food and uses it for growth and maintenance
     2: a source of materials to nourish the body [syn: {nutriment},
         {nourishment}, {sustenance}, {aliment}, {alimentation}, {victuals}]
     3: the scientific study of food and drink (especially in
        humans)