Greek "Howling". As a general term, "goetia" refers to low magic (as opposed to Theurgy), involving the Evocation of evil spirits in an attempt to force them to fulfil ones material wishes. As a specific term, "The Goetia" is a part of "The Legemoton, or Lesser Key of Solomon" - a grimoire (which contains goetia) translated by Macgregor Mathers and edited by Aleister Crowley, which proved to be the catalyst for their falling out.