The Collaborative International Dictionary of English v.0.48:

Enforce \En*force"\, v. t. [imp. & p. p. Enforced; p. pr. &
   vb. n. Enforcing.] [OF. enforcier to strengthen, force, F.
   enforcir; pref. en- (L. in) + F. force. See Force.]
   1. To put force upon; to force; to constrain; to compel; as,
      to enforce obedience to commands.
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            Inward joy enforced my heart to smile. --Shak.
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   2. To make or gain by force; to obtain by force; as, to
      enforce a passage. "Enforcing furious way." --Spenser.
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   3. To put in motion or action by violence; to drive.
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            As swift as stones
            Enforced from the old Assyrian slings. --Shak.
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   4. To give force to; to strengthen; to invigorate; to urge
      with energy; as, to enforce arguments or requests.
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            Enforcing sentiment of the thrust humanity. --Burke.
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   5. To put in force; to cause to take effect; to give effect
      to; to execute with vigor; as, to enforce the laws.
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   6. To urge; to ply hard; to lay much stress upon.
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            Enforce him with his envy to the people. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Enforce \En*force\, v. i.
   1. To attempt by force. [Obs.]
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   2. To prove; to evince. [R.] --Hooker.
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   3. To strengthen; to grow strong. [Obs.] --Chaucer.
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The Collaborative International Dictionary of English v.0.48:

Enforce \En*force"\, n.
   Force; strength; power. [Obs.]
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         A petty enterprise of small enforce.     --Milton.
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WordNet (r) 3.0 (2006):

enforce
    v 1: ensure observance of laws and rules; "Apply the rules to
         everyone"; [syn: enforce, implement, apply] [ant:
         exempt, free, relieve]
    2: compel to behave in a certain way; "Social relations impose
       courtesy" [syn: enforce, impose]

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "enforce":
   abide by, accomplish, adhere to, administer, apply, bestow, bind,
   bring to bear, browbeat, bully, carry out, carry through, cause,
   cause to, coerce, compel, complete, constrain, demand, discharge,
   dose, dose with, drive, effect, effectuate, enforce upon, execute,
   fill out, force, force upon, fulfill, give, have, honor, impel,
   implement, impose, impose on, impose upon, impress upon, inflict,
   insist on, insist upon, intimidate, invoke, lay on, lean on, make,
   make out, mete out to, oblige, observe, perform, prescribe for,
   press, promulgate, prosecute, put in force, put in practice,
   put into effect, put into execution, put on, put through,
   put to use, put upon, railroad, reinforce, render, require,
   restrain, stress, support, tie, transact, use force upon