abracadabra

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A magical charm or incantation having the power to ward off disease or disaster.
• noun Foolish or unintelligible talk.

from The Century Dictionary.

• noun A cabalistic word used in incantations. When written in a manner similar to that shown in the accompanying diagram, so as to be read in different directions, and worn as an amulet, it was supposed to cure certain ailments.
• noun Hence Any word-charm or empty jingle of words.

from the GNU version of the Collaborative International Dictionary of English.

• noun A mystical word or collocation of letters written as in the figure. Worn on an amulet it was supposed to ward off fever. At present the word is used chiefly in jest to denote something without meaning; jargon.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• interjection Used to indicate that a magic trick or other illusion has been performed.
• noun Complicated technicalities, jargon that one does not understand much if at all.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun gibberish and nonsense