The Collaborative International Dictionary of English v.0.48:

Acquaint \Ac*quaint"\, a. [OF. acoint. See Acquaint, v. t.]
   Acquainted. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Acquaint \Ac*quaint"\, v. t. [imp. & p. p. Acquainted; p. pr.
   & vb. n. Acquainting.] [OE. aqueinten, acointen, OF.
   acointier, LL. adcognitare, fr. L. ad + cognitus, p. p. of
   cognoscere to know; con- + noscere to know. See Quaint,
   Know.]
   1. To furnish or give experimental knowledge of; to make
      (one) to know; to make familiar; -- followed by with.
      [1913 Webster]

            Before a man can speak on any subject, it is
            necessary to be acquainted with it.   --Locke.
      [1913 Webster]

            A man of sorrows and acquainted with grief. --Isa.
                                                  liii. 3.
      [1913 Webster]

   2. To communicate notice to; to inform; to make cognizant; --
      followed by with (formerly, also, by of), or by that,
      introducing the intelligence; as, to acquaint a friend
      with the particulars of an act.
      [1913 Webster]

            Acquaint her here of my son Paris' love. --Shak.
      [1913 Webster]

            I must acquaint you that I have received
            New dated letters from Northumberland. --Shak.
      [1913 Webster]

   3. To familiarize; to accustom. [Obs.] --Evelyn.
      [1913 Webster]

   To be acquainted with, to be possessed of personal
      knowledge of; to be cognizant of; to be more or less
      familiar with; to be on terms of social intercourse with.
      [1913 Webster]

   Syn: To inform; apprise; communicate; advise.
        [1913 Webster]

WordNet (r) 3.0 (2006):

acquaint
    v 1: cause to come to know personally; "permit me to acquaint
         you with my son"; "introduce the new neighbors to the
         community" [syn: introduce, present, acquaint]
    2: make familiar or conversant with; "you should acquaint
       yourself with your new computer"; "We familiarized ourselves
       with the new surroundings" [syn: familiarize,
       familiarise, acquaint]
    3: inform; "Please acquaint your colleagues of your plans to
       move"

Moby Thesaurus II by Grady Ward, 1.0:

40 Moby Thesaurus words for "acquaint":
   accustom, advertise, advertise of, advise, apprise, brief,
   bring word, clue, communicate, disclose, divulge, do the honors,
   enlighten, familiarize, fill in, give a knockdown,
   give an introduction, give notice, give the facts, give word,
   habituate, inform, instruct, introduce, leave word, let know,
   make acquainted, mention to, notify, post, present, quaint, report,
   reveal, send word, serve notice, speak, tell, verse, warn