The Collaborative International Dictionary of English v.0.48:

Authorization \Au`thor*i*za"tion\, n. [Cf. F. autorisation.]
   The act of giving authority or legal power; establishment by
   authority; sanction or warrant.
   [1913 Webster]

         The authorization of laws.               --Motley.
   [1913 Webster]

         A special authorization from the chief.  --Merivale.
   [1913 Webster]

WordNet (r) 3.0 (2006):

authorization
    n 1: a document giving an official instruction or command [syn:
         mandate, authorization, authorisation]
    2: the power or right to give orders or make decisions; "he has
       the authority to issue warrants"; "deputies are given
       authorization to make arrests"; "a place of potency in the
       state" [syn: authority, authorization, authorisation,
       potency, dominance, say-so]
    3: official permission or approval; "authority for the program
       was renewed several times" [syn: authority,
       authorization, authorisation, sanction]
    4: the act of conferring legality or sanction or formal warrant
       [syn: authorization, authorisation, empowerment]

Moby Thesaurus II by Grady Ward, 1.0:

187 Moby Thesaurus words for "authorization":
   John Hancock, OK, acceptance, accession, accredit, acme, advance,
   affidavit, affirmance, affirmation, agency, agentship, aid, allow,
   allowance, anointing, anointment, appointment, approbation,
   approval, approve, arrogation, assignment, assist, assumption,
   attestation, authentication, authority, be-all and end-all,
   bill of health, blue ribbon, brevet, care, certificate,
   certificate of proficiency, certification, championship, charge,
   clearance, command, commission, commissioning, commitment,
   confirmation, consecration, consent, consignment, control,
   coronation, countenance, countersignature, credential, cure,
   delegated authority, delegation, deposition, deputation,
   devolution, devolvement, diploma, directorship, dominion,
   effectiveness, election, embassy, empower, empowerment, enable,
   enabling, enactment, endorse, endorsement, enfranchisement,
   entitlement, entrusting, entrustment, errand, executorship,
   exequatur, facilitate, factorship, fiat, first place, first prize,
   forward, full power, further, go-ahead, green light, headship,
   hegemony, height, help, highest, imperium, imprimatur, influence,
   jurisdiction, kingship, leadership, leave, legalization, legation,
   legislation, legitimate succession, legitimatization, let, license,
   lieutenancy, lordship, management, mandate, mastership, mastery,
   maximum, mission, most, navicert, ne plus ultra, new high, nod,
   notarization, notarized statement, note, office, okay, palms,
   paramountcy, permission, permit, plenipotentiary power, power,
   power of attorney, power to act, presidency, primacy, procuration,
   promote, proxy, purview, qualify, ratification, record, regency,
   regentship, responsibility, rubber stamp, rule, sanction, say,
   seal, seizure, sheepskin, sigil, signature, signet, sovereignty,
   stamp, stamp of approval, subscription, subserve, succession,
   sufferance, support, supremacy, sway, sworn statement, taking over,
   task, testamur, testimonial, the nod, ticket, top spot, trust,
   trusteeship, usurpation, validation, vest, vicarious authority,
   visa, vise, voucher, warrant, warranty, witness, zenith