The Collaborative International Dictionary of English v.0.48:

Ignorant \Ig"no*rant\, a. [F., fr. L. ignorans, -antis, p. pr.
   of ignorare to be ignorant. See Ignore.]
   1. Destitute of knowledge; uninstructed or uninformed;
      untaught; unenlightened.
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            He that doth not know those things which are of use
            for him to know, is but an ignorant man, whatever he
            may know besides.                     --Tillotson.
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   2. Unacquainted with; unconscious or unaware; -- used with
      of.
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            Ignorant of guilt, I fear not shame.  --Dryden.
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   3. Unknown; undiscovered. [Obs.]
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            Ignorant concealment.                 --Shak.
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            Alas, what ignorant sin have I committed? --Shak.
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   4. Resulting from ignorance; foolish; silly.
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            His shipping,
            Poor ignorant baubles! -- on our terrible seas,
            Like eggshells moved.                 --Shak.

   Syn: Uninstructed; untaught; unenlightened; uninformed;
        unlearned; unlettered; illiterate. -- Ignorant,
        Illiterate. Ignorant denotes lack of knowledge, either
        as to single subject or information in general;
        illiterate refers to an ignorance of letters, or of
        knowledge acquired by reading and study. In the Middle
        Ages, a great proportion of the higher classes were
        illiterate, and yet were far from being ignorant,
        especially in regard to war and other active pursuits.
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              In such business
              Action is eloquence, and the eyes of the ignorant
              More learned than the ears.         --Shak.
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              In the first ages of Christianity, not only the
              learned and the wise, but the ignorant and
              illiterate, embraced torments and death.
                                                  --Tillotson.
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The Collaborative International Dictionary of English v.0.48:

Ignorant \Ig"no*rant\, n.
   A person untaught or uninformed; one unlettered or unskilled;
   an ignoramous.
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         Did I for this take pains to teach
         Our zealous ignorants to preach?         --Denham.
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WordNet (r) 3.0 (2006):

ignorant
    adj 1: uneducated in general; lacking knowledge or
           sophistication; "an ignorant man"; "nescient of
           contemporary literature"; "an unlearned group incapable
           of understanding complex issues"; "exhibiting contempt
           for his unlettered companions" [syn: ignorant,
           nescient, unlearned, unlettered]
    2: uneducated in the fundamentals of a given art or branch of
       learning; lacking knowledge of a specific field; "she is
       ignorant of quantum mechanics"; "he is musically illiterate"
       [syn: ignorant, illiterate]
    3: unaware because of a lack of relevant information or
       knowledge; "he was completely ignorant of the circumstances";
       "an unknowledgeable assistant"; "his rudeness was unwitting"
       [syn: ignorant, unknowledgeable, unknowing,
       unwitting]