The Collaborative International Dictionary of English v.0.48:

Accusation \Ac`cu*sa"tion\, n. [OF. acusation, F. accusation, L.
   accusatio, fr. accusare. See Accuse.]
   [1913 Webster]
   1. The act of accusing or charging with a crime or with a
      lighter offense.
      [1913 Webster]

            We come not by the way of accusation
            To taint that honor every good tongue blesses.
                                                  --Shak.
      [1913 Webster]

   2. That of which one is accused; the charge of an offense or
      crime, or the declaration containing the charge.
      [1913 Webster]

            [They] set up over his head his accusation. --Matt.
                                                  xxvii. 37.
      [1913 Webster]

   Syn: Impeachment; crimination; censure; charge.
        [1913 Webster]

WordNet (r) 3.0 (2006):

accusation
    n 1: a formal charge of wrongdoing brought against a person; the
         act of imputing blame or guilt [syn: accusation,
         accusal]
    2: an assertion that someone is guilty of a fault or offence;
       "the newspaper published charges that Jones was guilty of
       drunken driving" [syn: accusation, charge]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

ACCUSATION, crim. law. A charge made to a competent officer against one who
has committed a crime or misdemeanor, so that he may be brought to justice
and punishment.
     2. A neglect to accuse may in some cases be considered a misdemeanor,
or misprision. (q.v.) 1 Bro. Civ. Law, 247; 2 Id. 389; Inst. lib. 4, tit.
18.
     3. It is a rule that no man is bound to accuse himself, or to testify
against himself in a criminal case. Accusare nemo se debet nisi coram Deo.
Vide Evidence; Interest; Witness.