Source : Webster's Revised Unabridged Dictionary (1913)

Acquaintance \Ac*quaint"ance\, n. [OE. aqueintance, OF.
   acointance, fr. acointier. See {Acquaint}.]
   1. A state of being acquainted, or of having intimate, or
      more than slight or superficial, knowledge; personal
      knowledge gained by intercourse short of that of
      friendship or intimacy; as, I know the man; but have no
      acquaintance with him.

            Contract no friendship, or even acquaintance, with a
            guileful man.                         --Sir W.
                                                  Jones.

   2. A person or persons with whom one is acquainted.

            Montgomery was an old acquaintance of Ferguson.
                                                  --Macaulay.

   Note: In this sense the collective term acquaintance was
         formerly both singular and plural, but it is now
         commonly singular, and has the regular plural
         acquaintances.

   {To be of acquaintance}, to be intimate.

   {To take acquaintance of} or {with}, to make the acquaintance
      of. [Obs.]

   Syn: Familiarity; intimacy; fellowship; knowledge.

   Usage: {Acquaintance}, {Familiarity}, {Intimacy}. These words
          mark different degrees of closeness in social
          intercourse. Acquaintance arises from occasional
          intercourse; as, our acquaintance has been a brief
          one. We can speak of a slight or an intimate
          acquaintance. Familiarity is the result of continued
          acquaintance. It springs from persons being frequently
          together, so as to wear off all restraint and reserve;
          as, the familiarity of old companions. Intimacy is the
          result of close connection, and the freest interchange
          of thought; as, the intimacy of established
          friendship.

                Our admiration of a famous man lessens upon our
                nearer acquaintance with him.     --Addison.

                We contract at last such a familiarity with them
                as makes it difficult and irksome for us to call
                off our minds.                    --Atterbury.

                It is in our power to confine our friendships
                and intimacies to men of virtue.  --Rogers.

Source : WordNet®

acquaintance
     n 1: personal knowledge or information about someone or something
          [syn: {familiarity}, {conversance}, {conversancy}]
     2: a relationship less intimate than friendship [syn: {acquaintanceship}]
     3: a person with whom you are acquainted; "I have trouble
        remembering the names of all my acquaintances"; "we are
        friends of the family" [syn: {friend}]