Source : Webster's Revised Unabridged Dictionary (1913)

Apportion \Ap*por"tion\, v. t. [imp. & p. p. {Apportioned}; p.
   pr. & vb. n. {Apportioning}.] [OF. apportionner, LL.
   apportionare, fr. L. ad + portio. See {Portion}.]
   To divide and assign in just proportion; to divide and
   distribute proportionally; to portion out; to allot; as, to
   apportion undivided rights; to apportion time among various
   employments.

Source : WordNet®

apportioning
     n : the act of distributing by allotting or apportioning;
         distribution according to a plan; "the apportionment of
         seats in the House of Representatives is based on the
         relative population of each state" [syn: {allotment}, {apportionment},
          {allocation}, {parceling}, {parcelling}, {assignation}]