il·lit·er·ate
/i(l)ˈlidərət/
adjective
adjective: illiterate
unable to read or write.
“his parents were illiterate”
Similar:
unable to read or write
unlettered
analphabetic
functionally illiterate
Opposite:
literate
ignorant in a particular subject or activity.
“the extent to which voters are politically illiterate”
Similar:
ignorant
unknowledgeable
uneducated
untaught
unschooled
untutored
untrained
uninstructed
uninformed
unlearned
unread
unenlightened
benighted
backward
nescient
Opposite:
literate
knowledgeable
uncultured or poorly educated.
“the ignorant, illiterate Town Council”
(especially of a piece of writing) showing a lack of education, especially an inability to read or write well.
“as you can see, I have corrected your misspelled, illiterate letter”

It doesn’t simply mean unable to read or write.