Literate means to read and write while illiterate means the opposite.
Accurate is the one that comes to mind.
There is no one-word 8-letter palindrome in English, apparently!
to simplify.
Cloister
An 8 letter word that means the inside of anything might be "interior." This word has 8 letters and would probably fit your crossword puzzle clue.
"Endorsement" is an 8-letter word that means official approval or support.
birthday
famished
friction
accurate
transfer
allocate
Isolated
The 8-letter "f" word in science that means force is "friction."
Darkness.
Abnormal