(adjective) lacking facility in reading and writing and ignorant of the knowledge to be gained from books / (adjective) illiterate / (adjective) not marked with letters
In the mouths of unlettered people she finds the bliss of quotidian metaphor:
I don't think I've seen this word used before but the meaning is pretty clear
In 1937, black readers were embarrassed by the unlettered nature of the dialogue
Naipaul claimed that he had not even been published in America until the 1970s, 'and then the reviews were awful--unlettered, illiterate, ignorant'.