Abrahadabra's a word that first publicly appeared in The Book of the Law, the central sacred text of Thelema. Its author, Aleister Crowley, described it as the "the Word of the Aeon, which signifieth The Great Work accomplished." This's in reference to his belief that the writing of Liber Legis heralded a new Aeon for mankind that was ruled by the god Ra-Hoor-Khuit (a form of Horus). Abrahadabra's, therefore, the "magical formula" of this new age. It isn't to be confused with the Word of the Law… (More on Abrahadabra)