The Collaborative International Dictionary of English v.0.48:

Acquiesce \Ac`qui*esce"\, v. i. [imp. & p. p. Acquiesced; p.
   pr. & vb. n. Acquiescing] [L. acquiescere; ad + quiescere
   to be quiet, fr. quies rest: cf. F. acquiescer. See Quiet.]
   1. To rest satisfied, or apparently satisfied, or to rest
      without opposition and discontent (usually implying
      previous opposition or discontent); to accept or consent
      by silence or by omitting to object; -- followed by in,
      formerly also by with and to.
      [1913 Webster]

            They were compelled to acquiesce in a government
            which they did not regard as just.    --De Quincey.
      [1913 Webster]

   2. To concur upon conviction; as, to acquiesce in an opinion;
      to assent to; usually, to concur, not heartily but so far
      as to forbear opposition.
      [1913 Webster]

   Syn: To submit; comply; yield; assent; agree; consent;
        accede; concur; conform; accept tacitly.
        [1913 Webster]

WordNet (r) 3.0 (2006):

acquiesce
    v 1: to agree or express agreement; "The Maestro assented to the
         request for an encore" [syn: assent, accede,
         acquiesce] [ant: dissent]