It seemed that he was called an ignorant in jealous contempt because he could not read or write classical Chinese correctly, nor understand Chinese words in conversation, which was a general education for the samurai class at that time.
ただ当時の武士の教養であった漢文を正確に読み書きできず、話中の漢語が理解できなかったから、彼らから嫉みも込めて無学と呼ばれたと思われる。