The Collaborative International Dictionary of English v.0.48:

Empower \Em*pow"er\, v. t. [imp. & p. p. Empowered; p. pr. &
   vb. n. Empowering.]
   1. To give authority to; to delegate power to; to commission;
      to authorize (having commonly a legal force); as, the
      Supreme Court is empowered to try and decide cases, civil
      or criminal; the attorney is empowered to sign an
      acquittance, and discharge the debtor.
      [1913 Webster]

   2. To give moral or physical power, faculties, or abilities
      to. "These eyes . . . empowered to gaze." --Keble.
      [1913 Webster]

   3. to enable or permit; to give more opportunity for
      independent action.
      [PJC]

WordNet (r) 3.0 (2006):

empower
    v 1: give or delegate power or authority to; "She authorized her
         assistant to sign the papers" [syn: empower, authorise,
         authorize]
    2: give qualities or abilities to [syn: endow, indue,
       gift, empower, invest, endue]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "empower":
   accredit, arm, assign, authorize, certificate, certify, charge,
   charter, clothe, clothe with power, commission, commit, consign,
   delegate, depute, deputize, detach, detail, devolute, devolve,
   devolve upon, enable, endow, endue, enfranchise, entitle, entrust,
   franchise, give in charge, give official sanction, give power,
   invest, legalize, legitimize, license, mission, patent, post,
   privilege, ratify, sanction, send out, transfer, validate, vest,
   warrant