The Collaborative International Dictionary of English v.0.48:

Sanction \Sanc"tion\, n. [L. sanctio, from sancire, sanctum to
   render sacred or inviolable, to fix unalterably: cf. F.
   sanction. See Saint.]
   1. Solemn or ceremonious ratification; an official act of a
      superior by which he ratifies and gives validity to the
      act of some other person or body; establishment or
      furtherance of anything by giving authority to it;
      confirmation; approbation.
      [1913 Webster]

            The strictest professors of reason have added the
            sanction of their testimony.          --I. Watts.
      [1913 Webster]

   2. Anything done or said to enforce the will, law, or
      authority of another; as, legal sanctions.
      [1913 Webster]

   Syn: Ratification; authorization; authority; countenance;
        support.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sanction \Sanc"tion\, v. t. [imp. & p. p. Sanctioned; p. pr. &
   vb. n. Sanctioning.]
   To give sanction to; to ratify; to confirm; to approve.
   [1913 Webster]

         Would have counseled, or even sanctioned, such perilous
         experiments.                             --De Quincey.
   [1913 Webster]

   Syn: To ratify; confirm; authorize; countenance.
        [1913 Webster]

WordNet (r) 3.0 (2006):

sanction
    n 1: formal and explicit approval; "a Democrat usually gets the
         union's endorsement" [syn: sanction, countenance,
         endorsement, indorsement, warrant, imprimatur]
    2: a mechanism of social control for enforcing a society's
       standards
    3: official permission or approval; "authority for the program
       was renewed several times" [syn: authority,
       authorization, authorisation, sanction]
    4: the act of final authorization; "it had the sanction of the
       church"
    v 1: give sanction to; "I approve of his educational policies"
         [syn: approve, O.K., okay, sanction] [ant:
         disapprove, reject]
    2: give authority or permission to
    3: give religious sanction to, such as through on oath;
       "sanctify the marriage"

Moby Thesaurus II by Grady Ward, 1.0:

198 Moby Thesaurus words for "sanction":
   John Hancock, OK, accede to, accept, acceptance, accord, accord to,
   accredit, acquiescence, adherence, admiration, admire, advocacy,
   advocate, affirm, affirmance, affirmation, affirmative,
   affirmative voice, agree to, agreement, aid, allow, allowance,
   amen, approbation, approval, approve, approve of, assent,
   authenticate, authentication, authority, authorization, authorize,
   autograph, aye, back, backing, ban, be willing, bless, blessing,
   certificate, certification, certify, charter, clearance,
   commission, compliance, concurrence, condescend, confirm,
   confirmation, connivance, connive at, consent, consent to,
   consent to silently, constitute, cosign, countenance, countersign,
   countersignature, declare lawful, decree, deign, discipline,
   eagerness, empower, empowerment, enable, enabling, enact,
   enactment, encourage, encouragement, endorse, endorsement,
   enfranchise, enfranchisement, entitle, entitlement, establish,
   esteem, favor, favorable vote, fiat, formulate, franchise,
   give consent, give official sanction, give permission, give power,
   give the go-ahead, give the imprimatur, give thumbs up,
   go along with, go-ahead, grant, green light, have no objection,
   help, hold with, imprimatur, initial, keep in countenance, leave,
   legalization, legalize, legislate, legislation, legitimate,
   legitimatization, legitimatize, legitimization, legitimize,
   license, make a regulation, make legal, nod, nod assent,
   not refuse, notarization, notarize, okay, ordain, pass, pass on,
   pass upon, patent, penalty, permission, permit, prescribe,
   privilege, promptitude, promptness, punishment, put in force,
   ratification, ratify, readiness, recommendation, redress, regulate,
   respect, retaliation, retribution, rubber stamp, say amen to,
   say aye, say yes, seal, seal of approval, second, sigil, sign,
   sign and seal, signature, signet, sponsor, sponsorship, stamp,
   stamp of approval, submission, subscribe to, subscription,
   sufferance, support, swear and affirm, swear to, take kindly to,
   the nod, think well of, undersign, underwrite, ungrudgingness,
   unloathness, unreluctance, uphold, validate, validation,
   view with favor, visa, vise, voice, vote, vote affirmatively,
   vote aye, vouchsafe, warrant, warranty, willingness, wink at, yea,
   yea vote, yield assent



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

SANCTION. That part of a law which inflicts a penalty for its violation, or
bestows a reward for its observance. Sanctions are of two kinds, those which
redress civil injuries, called civil sanctions; and those which punish
crimes, called penal sanctions. 1 Hoffm. Leg. Outl. 279; Just. Ins. lib. 2,
t. 1, Sec. 10; Ruthf. Inst. b. 2, c. 6, s. 6; Toull. tit. prel. 86; Ferguss.
Inst. of Mor. Phil. p. 4, c. 3, s. 13, and p. 6, c. 1, et seq; 1 Bl. Com.
56.