The Collaborative International Dictionary of English v.0.48:

Slander \Slan"der\, v. t. [imp. & p. p. Slandered; p. pr. &
   vb. n. Slandering.]
   1. To defame; to injure by maliciously uttering a false
      report; to tarnish or impair the reputation of by false
      tales maliciously told or propagated; to calumniate.
      [1913 Webster]

            O, do not slander him, for he is kind. --Shak.
      [1913 Webster]

   2. To bring discredit or shame upon by one's acts.
      [1913 Webster]

            Tax not so bad a voice
            To slander music any more than once.  --Shak.
      [1913 Webster]

   Syn: To asperse; defame; calumniate; vilify; malign; belie;
        scandalize; reproach. See Asperse.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Slander \Slan"der\, n. [OE. sclandere, OF. esclandre, esclandle,
   escandre, F. esclandre, fr. L. scandalum, Gr. ??? a snare,
   stumbling block, offense, scandal; probably originally, the
   spring of a trap, and akin to Skr. skand to spring, leap. See
   Scan, and cf. Scandal.]
   1. A false tale or report maliciously uttered, tending to
      injure the reputation of another; the malicious utterance
      of defamatory reports; the dissemination of malicious
      tales or suggestions to the injury of another.
      [1913 Webster]

            Whether we speak evil of a man to his face or behind
            his back; the former way, indeed, seems to be the
            most generous, but yet is a great fault, and that
            which we call "reviling;" the latter is more mean
            and base, and that which we properly call "slander",
            or "Backbiting."                      --Tillotson.
      [1913 Webster]

            [We] make the careful magistrate
            The mark of slander.                  --B. Jonson.
      [1913 Webster]

   2. Disgrace; reproach; dishonor; opprobrium.
      [1913 Webster]

            Thou slander of thy mother's heavy womb. --Shak.
      [1913 Webster]

   3. (Law) Formerly, defamation generally, whether oral or
      written; in modern usage, defamation by words spoken;
      utterance of false, malicious, and defamatory words,
      tending to the damage and derogation of another; calumny.
      See the Note under Defamation. --Burril.
      [1913 Webster]

WordNet (r) 3.0 (2006):

slander
    n 1: words falsely spoken that damage the reputation of another
    2: an abusive attack on a person's character or good name [syn:
       aspersion, calumny, slander, defamation,
       denigration]
    v 1: charge falsely or with malicious intent; attack the good
         name and reputation of someone; "The journalists have
         defamed me!" "The article in the paper sullied my
         reputation" [syn: defame, slander, smirch, asperse,
         denigrate, calumniate, smear, sully, besmirch]