The Collaborative International Dictionary of English v.0.48:

Prejudice \Prej"u*dice\, n. [F. pr['e]judice, L. praejudicium;
   prae before + judicium judgment. See Prejudicate,
   Judicial.]
   1. Foresight. [Obs.]
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            Naught might hinder his quick prejudize. --Spenser.
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   2. An opinion or judgment formed without due examination;
      prejudgment; a leaning toward one side of a question from
      other considerations than those belonging to it; an
      unreasonable predilection for, or objection against,
      anything; especially, an opinion or leaning adverse to
      anything, without just grounds, or before sufficient
      knowledge.
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            Though often misled by prejudice and passion, he was
            emphatically an honest man.           --Macaulay.
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   3. (Law) A bias on the part of judge, juror, or witness which
      interferes with fairness of judgment.
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   4. Mischief; hurt; damage; injury; detriment. --Locke.
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            England and France might, through their amity,
            Breed him some prejudice.             --Shak.
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   Syn: Prejudgment; prepossession; bias; harm; hurt; damage;
        detriment; mischief; disadvantage.
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The Collaborative International Dictionary of English v.0.48:

Prejudice \Prej"u*dice\, v. t. [imp. & p. p. Prejudiced; p.
   pr. & vb. n. Prejudicing.] [Cf. F. pr['e]judicier. See
   Prejudice, n.]
   1. To cause to have prejudice; to prepossess with opinions
      formed without due knowledge or examination; to bias the
      mind of, by hasty and incorrect notions; to give an
      unreasonable bent to, as to one side or the other of a
      cause; as, to prejudice a critic or a juryman.
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            Suffer not any beloved study to prejudice your mind
            so far as to despise all other learning. --I. Watts
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   2. To obstruct or injure by prejudices, or by previous bias
      of the mind; hence, generally, to hurt; to damage; to
      injure; to impair; as, to prejudice a good cause.
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            Seek how may prejudice the foe.       --Shak
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WordNet (r) 3.0 (2006):

prejudice
    n 1: a partiality that prevents objective consideration of an
         issue or situation [syn: bias, prejudice,
         preconception]
    v 1: disadvantage by prejudice
    2: influence (somebody's) opinion in advance [syn: prejudice,
       prepossess]

The Devil's Dictionary (1881-1906):

PREJUDICE, n.  A vagrant opinion without visible means of support.