The Collaborative International Dictionary of English v.0.48:

Abandonment \A*ban"don*ment\ (-ment), n. [Cf. F. abandonnement.]
   1. The act of abandoning, or the state of being abandoned;
      total desertion; relinquishment.
      [1913 Webster]

            The abandonment of the independence of Europe.
                                                  --Burke.
      [1913 Webster]

   2. (Mar. Law) The relinquishment by the insured to the
      underwriters of what may remain of the property insured
      after a loss or damage by a peril insured against.
      [1913 Webster]

   3. (Com. Law)
      (a) The relinquishment of a right, claim, or privilege, as
          to mill site, etc.
      (b) The voluntary leaving of a person to whom one is bound
          by a special relation, as a wife, husband, or child;
          desertion.
          [1913 Webster]

   4. Careless freedom or ease; abandon. [R.] --Carlyle.
      [1913 Webster]

WordNet (r) 3.0 (2006):

abandonment
    n 1: the act of giving something up [syn: abandonment,
         forsaking, desertion]
    2: withdrawing support or help despite allegiance or
       responsibility; "his abandonment of his wife and children
       left them penniless" [syn: desertion, abandonment,
       defection]
    3: the voluntary surrender of property (or a right to property)
       without attempting to reclaim it or give it away