JH knows "mistake"

JH was doing grammar...looking up vocabulary words in the dictionary. Wanting to be up heelying around and playing instead of sitting still looking up vocab, he was a little put out. A word came up that he had looked up a while ago: mistake. He turns to me with his arms crossed and pouty look and says, "I've already looked up mistake. It means an err or dis-understanding." I couldn't help but laugh and he did too.