Ignorant, illiterate, unlettered, uneducated, untaught, untutored, unlearned mean not having knowledge.
One is ignorant who is without knowledge, whether in general or of some particular thing.
One is illiterate who is without the necessary rudiments of education; the term may imply a failure to attain a standard set for the educated or cultivated man, but when directly applied to a person it usually implies inability to read or write.
When applied to words or alterations of words or grammatical constructions, it implies violation of the usage of educated men or a status below that of the standard English of the day; thus, most teachers would stigmatize the expression “I seen it” as illiterate. The word, however, is often used merely as a contemptuous description of one (as a person, an utterance, or a letter) that shows little evidence of education or cultivation or shows inability to read and understand.
One is unlettered who is without the learning that is to be gained through the knowledge of books. Often it implies being able to read and write, but with no facility in either reading or writing, but sometimes it implies general ignorance or illiteracy.
One is uneducated, untaught, untutored, or unlearned who either has had no training in the schools or under teachers or whose ignorance, or crudeness, or general lack of intelligence suggests such a lack; none of the words, however, is used with great precision or in a strict sense.