The Collaborative International Dictionary of English v.0.48:

Despise \De*spise"\, v. t. [imp. & p. p. Despised; p. pr. &
   vb. n. Despising.] [OF. despis-, in some forms of despire
   to despise, fr. L. despicere, despectum, to look down upon,
   despise; de- + spicere, specere, to look. See Spy, and cf.
   Despicable, Despite.]
   To look down upon with disfavor or contempt; to contemn; to
   scorn; to disdain; to have a low opinion or contemptuous
   dislike of.
   [1913 Webster]

         Fools despise wisdom and instruction.    --Prov. i. 7.
   [1913 Webster]

         Men naturally despise those who court them, but respect
         those who do not give way to them.       --Jowett
                                                  (Thucyd. ).

   Syn: To contemn; scorn; disdain; slight; undervalue. See
        Contemn.
        [1913 Webster]

WordNet (r) 3.0 (2006):

despise
    v 1: look down on with disdain; "He despises the people he has
         to work for"; "The professor scorns the students who don't
         catch on immediately" [syn: contemn, despise, scorn,
         disdain]

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "despise":
   abhor, abjure, abominate, avoid, be above, be contemptuous of,
   brush aside, care nothing for, chuck, chuck out, contemn,
   contradict, decline, deny, deride, detest, disapprove, discard,
   disclaim, discount, disdain, dismiss, disown, disparage, disprize,
   disregard, dump on, eschew, except, exclude, execrate,
   feel contempt for, feel superior to, flout, forswear, hate,
   hold beneath one, hold cheap, hold in contempt, hold in derision,
   ignore, insult, laugh at, laugh to scorn, loathe, look down upon,
   misprize, overlook, pass by, pass up, push aside, put down,
   rank low, rebuff, recant, refuse, refuse to consider, reject,
   renounce, repel, repudiate, repulse, ridicule, scoff at, scorn,
   scout, set at defiance, set at naught, shove away, shun, slight,
   slight over, sneer at, sneeze at, sniff at, snort at, snub, spurn,
   think nothing of, throw away, throw out, treat with contempt,
   turn away, turn out, waive