The Collaborative International Dictionary of English v.0.48:

Countenance \Coun"te*nance\ (koun"t[-e]*nans), n. [OE.
   contenance, countenaunce, demeanor, composure, F. contenance
   demeanor, fr. L. continentia continence, LL. also, demeanor,
   fr. L. continere to hold together, repress, contain. See
   Contain, and cf. Continence.]
   1. Appearance or expression of the face; look; aspect; mien.
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            So spake the Son, and into terror changed
            His countenance.                      --Milton.
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   2. The face; the features.
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            In countenance somewhat doth resemble you. --Shak.
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   3. Approving or encouraging aspect of face; hence, favor,
      good will, support; aid; encouragement.
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            Thou hast made him . . . glad with thy countenance.
                                                  --Ps. xxi. 6.
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            This is the magistrate's peculiar province, to give
            countenance to piety and virtue, and to rebuke vice.
                                                  --Atterbury.
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   4. Superficial appearance; show; pretense. [Obs.]
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            The election being done, he made countenance of
            great discontent thereat.             --Ascham.
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   In countenance, in an assured condition or aspect; free
      from shame or dismay. "It puts the learned in countenance,
      and gives them a place among the fashionable part of
      mankind." --Addison.

   Out of countenance, not bold or assured; confounded;
      abashed. "Their best friends were out of countenance,
      because they found that the imputations . . . were well
      grounded." --Clarendon.

   To keep the countenance, to preserve a composed or natural
      look, undisturbed by passion or emotion. --Swift.
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The Collaborative International Dictionary of English v.0.48:

Countenance \Coun"te*nance\ (koun"t?-nans), v. t. [imp. & p. p.
   Countenanced (-nanst); p. pr. & vb. n. Countenancing.]
   1. To encourage; to favor; to approve; to aid; to abet.
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            This conceit, though countenanced by learned men, is
            not made out either by experience or reason. --Sir
                                                  T. Browne.
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            Error supports custom, custom countenances error.
                                                  --Milton.
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   2. To make a show of; to pretend. [Obs.]
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            Which to these ladies love did countenance.
                                                  --Spenser.
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WordNet (r) 3.0 (2006):

countenance
    n 1: the appearance conveyed by a person's face; "a pleasant
         countenance"; "a stern visage" [syn: countenance,
         visage]
    2: formal and explicit approval; "a Democrat usually gets the
       union's endorsement" [syn: sanction, countenance,
       endorsement, indorsement, warrant, imprimatur]
    3: the human face (`kisser' and `smiler' and `mug' are informal
       terms for `face' and `phiz' is British) [syn: countenance,
       physiognomy, phiz, visage, kisser, smiler, mug]
    v 1: consent to, give permission; "She permitted her son to
         visit her estranged husband"; "I won't let the police
         search her basement"; "I cannot allow you to see your exam"
         [syn: permit, allow, let, countenance] [ant:
         disallow, forbid, interdict, nix, prohibit,
         proscribe, veto]

Moby Thesaurus II by Grady Ward, 1.0:

175 Moby Thesaurus words for "countenance":
   Buddha-like composure, OK, Oriental calm, abet, abetment, accept,
   acceptance, adherence, admiration, admire, advocacy, advocate,
   aegis, aid and abet, air, applaud, approbation, approval, approve,
   approve of, ask for, auspices, authority, authorization, back,
   backing, bear, bear with, bearing, bless, blessing, blink at,
   brook, brow, calm disposition, calm of mind, calmness, care,
   carriage, cast, cast of countenance, certification, champion,
   championship, charity, clearance, color, comfort, commend,
   complexion, composure, condone, connive at, cool, coolheadedness,
   coolness, demeanor, dial, easy mind, embolden, empowerment,
   enabling, encourage, encouragement, endorse, endorsement, endure,
   enfranchisement, entitlement, esteem, face, facial appearance,
   facies, favor, favorable vote, feature, features, feed, fiat,
   foster, fosterage, garb, give encouragement, go for, goodwill,
   grin and abide, guidance, guise, have, hear of, hearten, hold with,
   icy calm, imperturbation, indisturbance, indulge, interest, invite,
   keep in countenance, kisser, let go by, let pass, lineaments,
   lines, looks, map, mental composure, mien, mug, mush, nod, nourish,
   nurture, obey, overlook, pan, patronage, peace of mind,
   peacefulness, philosophic composure, philosophicalness, philosophy,
   phiz, physiognomy, placidity, port, posture, presence, puss,
   put up with, quiet, quiet mind, quietude, ratification, respect,
   rise above, sanction, sangfroid, seal of approval, seconding,
   serenity, shine upon, shrug, shrug it off, smile upon,
   soothingness, sponsorship, stamp of approval, stance, stand for,
   stomach, submit to, subscribe, suffer, support, sympathy,
   take kindly to, think well of, tolerate, traits, tranquillity,
   turn, tutelage, unruffledness, uphold, view with favor, visage,
   voice, vote, warrant, warranty, wink at, yea, yea vote, yield to