From the Wikipedia: Zenzizenzizenzic is an obsolete form of mathematical notation representing the eighth power of a number (that is, the zenzizenzizenzic of a number x is the power x8), dating from a time when powers were written out in words rather than as superscript numbers. This term was suggested by Robert Recorde, a 16th century Welsh writer of popular mathematics textbooks, in his work The Whetstone of Witte, published in 1557, although his spelling was zenzizenzizenzike; he wrote that it “doeth represent the square of squares squaredly”.
Also? It’s got more Zs in it than any other word in the Oxford English Dictionary. As someone with a Z in her name (Mary Suzanne), I approve.