The Collaborative International Dictionary of English v.0.48:

Accede \Ac*cede"\, v. i. [imp. & p. p. Acceded; p. pr. & vb.
   n. Acceding.] [L. accedere to approach, accede; ad + cedere
   to move, yield: cf. F. acc['e]dere. See Cede.]
   [1913 Webster]
   1. To approach; to come forward; -- opposed to recede.
      [Obs.] --T. Gale.
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   2. To enter upon an office or dignity; to attain.
      [1913 Webster]

            Edward IV., who had acceded to the throne in the
            year 1461.                            --T. Warton.
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            If Frederick had acceded to the supreme power.
                                                  --Morley.
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   3. To become a party by associating one's self with others;
      to give one's adhesion. Hence, to agree or assent to a
      proposal or a view; as, he acceded to my request.
      [1913 Webster]

            The treaty of Hanover in 1725 . . . to which the
            Dutch afterwards acceded.             --Chesterfield.
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   Syn: To agree; assent; consent; comply; acquiesce; concur.
        [1913 Webster]

WordNet (r) 3.0 (2006):

accede
    v 1: yield to another's wish or opinion; "The government bowed
         to the military pressure" [syn: submit, bow, defer,
         accede, give in]
    2: take on duties or office; "accede to the throne" [syn:
       accede, enter]
    3: to agree or express agreement; "The Maestro assented to the
       request for an encore" [syn: assent, accede, acquiesce]
       [ant: dissent]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "accede":
   OK, abide by, accede to, accept, acclaim, accord to, acquiesce,
   acquiesce in, agree, agree to, agree with, allow, applaud, approve,
   approve of, assent, attain to, be agreeable, be instated,
   be willing, buy, cheer, comply, concur, condescend, connive at,
   consent, consent to silently, cooperate, deign, endorse,
   face the music, give consent, give the nod, go along with, grant,
   hail, have no objection, hold with, in toto, knock under,
   knuckle down, knuckle under, let, live with it, mount the throne,
   nod, nod assent, not refuse, not resist, obey, okay, permit,
   ratify, receive, relent, resign, sanction, say aye, say yes,
   submit, subscribe, subscribe to, succumb, swallow it,
   swallow the pill, take, take it, take kindly to, take office,
   vote affirmatively, vote aye, vote for, welcome, wink at, yes,
   yield assent