illiterate

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Unable to read and write.
• adjective Having little or no formal education.
• adjective Marked by inferiority to an expected standard of familiarity with language and literature.
• adjective Violating prescribed standards of speech or writing.
• adjective Ignorant of the fundamentals of a given art or branch of knowledge.
• noun A person who is illiterate.
• noun People who are illiterate, considered as a group.

from The Century Dictionary.

• Ignorant of letters or books; having little or no learning; unlettered; uncultivated: as, the illiterate part of the population; an illiterate tribe.
• Showing illiteracy or want of culture; rude; barbarous.
• Synonyms Unlettered, Unlearned, etc. See ignorant.
• noun An illiterate person; one unable to read or to write.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Unable to read or write; ignorant of letters or books; unlettered; uninstructed; uneducated.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Unable to read and write.
• adjective Having less than an expected standard of familiarity with language and literature, or having little formal education.
• adjective Not conforming to prescribed standards of speech or writing.
• noun an illiterate person, one not able to read.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a person unable to read
• adjective not able to read or write
• adjective lacking culture, especially in language and literature
• adjective uneducated in the fundamentals of a given art or branch of learning; lacking knowledge of a specific field