The Collaborative International Dictionary of English v.0.48:

Sanctify \Sanc"ti*fy\, v. t. [imp. & p. p. Sanctified; p. pr.
   & vb. n. Sanctifying.] [F. sanctifier, L. sanctificare;
   sanctus holy + -ficare (in comp.) to make. See Saint, and
   -fy.]
   1. To make sacred or holy; to set apart to a holy or
      religious use; to consecrate by appropriate rites; to
      hallow.
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            God blessed the seventh day and sanctified it.
                                                  --Gen. ii. 3.
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            Moses . . . sanctified Aaron and his garments.
                                                  --Lev. viii.
                                                  30.
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   2. To make free from sin; to cleanse from moral corruption
      and pollution; to purify.
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            Sanctify them through thy truth.      --John xvii.
                                                  17.
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   3. To make efficient as the means of holiness; to render
      productive of holiness or piety.
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            A means which his mercy hath sanctified so to me as
            to make me repent of that unjust act. --Eikon
                                                  Basilike.
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   4. To impart or impute sacredness, venerableness,
      inviolability, title to reverence and respect, or the
      like, to; to secure from violation; to give sanction to.
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            The holy man, amazed at what he saw,
            Made haste to sanctify the bliss by law. --Dryden.
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            Truth guards the poet, sanctifies the line. --Pope.
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WordNet (r) 3.0 (2006):

sanctify
    v 1: render holy by means of religious rites [syn: consecrate,
         bless, hallow, sanctify] [ant: deconsecrate,
         desecrate, unhallow]
    2: make pure or free from sin or guilt; "he left the monastery
       purified" [syn: purify, purge, sanctify]

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "sanctify":
   aggrandize, apotheose, apotheosize, beatify, bless, canonize,
   cleanse, confirm, consecrate, crown, dedicate, deify, devote,
   elevate, ennoble, enshrine, enthrone, exalt, glamorize, glorify,
   hallow, immortalize, justify, legalize, legitimate, legitimatize,
   legitimize, license, lionize, magnify, make legendary, purify,
   raise, ratify, saint, sanction, set apart, set up, throne,
   uplift