No: HPFGUIDX 151028 Avada Kadavra and its relationships to abracadabra are mentioned extensively in Harry Potter companion books which have their own theories about HP. It is never mentioned in the six books by JKR and I was unable during a brief scan of JKR's quotes to find any mention from her at all but you can look more closely at www.quick-quote-quill.org katssirius