The Collaborative International Dictionary of English v.0.48:

Contemptuous \Con*temp"tu*ous\ (?; 135), a.
   Manifesting or expressing contempt or disdain; scornful;
   haughty; insolent; disdainful.
   [1913 Webster]

         A proud, contemptuous behavior.          --Hammond.
   [1913 Webster]

         Savage invective and contemptuous sarcasm. --Macaulay.
   [1913 Webster]

         Rome . . . entertained the most contemptuous opinion of
         the Jews.                                --Atterbury.

   Syn: Scornful; insolent; haughty; disdainful; supercilious;
        insulting; contumelious.

   Usage: Contemptuous, Contemptible. These words, from
          their similarity of sound, are sometimes erroneously
          interchanged, as when a person speaks of having "a
          very contemptible opinion of another." Contemptible is
          applied to that which is the object of contempt; as,
          contemptible conduct; acontemptible fellow.
          Contemptuous is applied to that which indicates
          contempt; as, a contemptuous look; a contemptuous
          remark; contemptuous treatment. A person, or whatever
          is personal, as an action, an expression, a feeling,
          an opinion, may be either contemptuous or
          contemptible; a thing may be contemptible, but can not
          be contemptuous.
          [1913 Webster]

WordNet (r) 3.0 (2006):

contemptuous
    adj 1: expressing extreme contempt [syn: contemptuous,
           disdainful, insulting, scornful]