ferlerberger
Ferlerberger is a word that is used to someone that was once something then forgot what it is to be like that. For example: If an old man yelled at a boy for something that boys do the man would prove he was a ferlerberger by forgeting that that is what boys do. for he was once a boy.
On page 826 of Harry Potter and the Order of the Phoenix Dumbledore proves to be a ferlerberger by forgeting how Harry might feel by being avoided and ignored.