The Collaborative International Dictionary of English v.0.48:

Authorize \Au"thor*ize\, v. t. [imp. & p. p. Authorized; p.
   pr. & vb. n. Authorizing.] [OE. autorize, F. autoriser, fr.
   LL. auctorizare, authorisare. See Author.]
   1. To clothe with authority, warrant, or legal power; to give
      a right to act; to empower; as, to authorize commissioners
      to settle a boundary.
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   2. To make legal; to give legal sanction to; to legalize; as,
      to authorize a marriage.
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   3. To establish by authority, as by usage or public opinion;
      to sanction; as, idioms authorized by usage.
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   4. To sanction or confirm by the authority of some one; to
      warrant; as, to authorize a report.
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            A woman's story at a winter's fire,
            Authorized by her grandam.            --Shak.
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   5. To justify; to furnish a ground for. --Locke.
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   To authorize one's self, to rely for authority. [Obs.]
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            Authorizing himself, for the most part, upon other
            histories.                            --Sir P.
                                                  Sidney.
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WordNet (r) 3.0 (2006):

authorize
    v 1: grant authorization or clearance for; "Clear the manuscript
         for publication"; "The rock star never authorized this
         slanderous biography" [syn: authorize, authorise,
         pass, clear]
    2: give or delegate power or authority to; "She authorized her
       assistant to sign the papers" [syn: empower, authorise,
       authorize]