The Collaborative International Dictionary of English v.0.48:

Enforcement \En*force"ment\, n. [Cf. OF. enforcement.]
   1. The act of enforcing; compulsion.
      [1913 Webster]

            He that contendeth against these enforcements may
            easily master or resist them.         --Sir W.
                                                  Raleigh.
      [1913 Webster]

            Confess 't was hers, and by what rough enforcement
            You got it from her.                  --Shak.
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   2. A giving force to; a putting in execution.
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            Enforcement of strict military discipline.
                                                  --Palfrey.
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   3. That which enforces, constraints, gives force, authority,
      or effect to; constraint; force applied.
      [1913 Webster]

            The rewards and punishment of another life, which
            the Almighty has established as the enforcements of
            his law.                              --Locke.
      [1913 Webster]

WordNet (r) 3.0 (2006):

enforcement
    n 1: the act of enforcing; ensuring observance of or obedience
         to

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "enforcement":
   carrying out, coaction, completion, compulsion, compulsiveness,
   constraint, discharge, effectuation, execution, forcing,
   fulfillment, inevitability, irresistibility, necessity, obligation,
   obligement, observance, prosecution, restraint, transaction