completely illiterate
Idiomatic expression meaning someone cannot read or write at all. Often used in the negative form 目に一丁字もない. The phrase is somewhat literary or emphatic.
See also: 目に一丁字もない
He is completely illiterate.
In the old days, many farmers were completely illiterate.
文盲 is a more direct noun meaning 'illiteracy' or 'illiterate person', while 目に一丁字なし is an idiomatic expression emphasizing total lack of reading ability.
The expression literally means 'not even one character in the eye', using 一丁字 (one character) to emphasize complete illiteracy. The exact historical origin is uncertain, but it is a classical Chinese-derived idiom.