A Discrimen is an emergency wish able to be given to another djinn or human. The word can only be recalled by the person in a time of emergency. In fact John Gaunt's discrimen was longer than Philippa's focus word, FABULONGOSHOOMARVELISHLYWONDERPIPICAL.
A discrimen is transmitted from the djinn to the recipient by a word. This is usually a very long word. If the recipient really needs to, he or she can easily remember and pronounce. There is, however, a disadvantage. If two discrimen used simultaneously, they cancel each other out.