The Collaborative International Dictionary of English v.0.48:

Allotment \Al*lot"ment\, n. [Cf. OF. alotement, F. allotement.]
   1. The act of allotting; assignment.
      [1913 Webster]

   2. That which is allotted; a share, part, or portion granted
      or distributed; that which is assigned by lot, or by the
      act of God; anything set apart for a special use or to a
      distinct party.
      [1913 Webster]

            The alloments of God and nature.      --L'Estrange.
      [1913 Webster]

            A vineyard and an allotment for olives and herbs.
                                                  --Broome.
      [1913 Webster]

   3. (law) The allowance of a specific amount of scrip or of a
      particular thing to a particular person.
      [1913 Webster]

   Cottage allotment, an allotment of a small portion of land
      to a country laborer for garden cultivation. [Eng.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

allotment
    n 1: a share set aside for a specific purpose [syn: allotment,
         allocation]
    2: 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,
       apportioning, allocation, parceling, parcelling,
       assignation]

Moby Thesaurus II by Grady Ward, 1.0:

116 Moby Thesaurus words for "allotment":
   C ration, K ration, aid, alimony, allocation, allowance, annuity,
   appointment, apportionment, appropriation, arrangement, array,
   arraying, assignment, assistance, big end, bigger half, bit, bite,
   board, bounty, budget, chunk, collation, collocation, commission,
   commons, constitution, contingent, cut, deal, depletion allowance,
   deployment, destiny, disposal, disposition, distribution, dividend,
   dole, earmarking, emergency rations, end, equal share, fate,
   fellowship, field rations, financial assistance, form, formation,
   formulation, grant, grant-in-aid, guaranteed annual income, half,
   halver, help, helping, interest, kitchen garden, lot,
   market garden, marshaling, meals, measure, meed, mess, modicum,
   moiety, old-age insurance, order, ordering, part, patch,
   pecuniary aid, pension, percentage, piece, placement, plot,
   portion, price support, proportion, public assistance,
   public welfare, quantum, quota, rake-off, ration, rations,
   regimentation, relief, retirement benefits, scholarship, segment,
   setting aside, share, short commons, slice, small share, stake,
   stipend, stock, structuring, subsidization, subsidy, subvention,
   support, syntax, tagging, tax benefit, tract, truck garden, tucker,
   welfare, welfare aid, welfare payments



Bouvier's Law Dictionary, Revised 6th Ed (1856):

ALLOTMENT. Distribution by lot; partition. Merl. Rep. h.t.