**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 *x*^{8}), dating from a time when powers were written out in words rather than as superscript numbers. This term was suggested byRobert Recorde, a 16th-century Welsh writer of popular mathematics textbooks, in his 1557 work *The Whetstone of Witte* (although his spelling was *zenzizenzizenzike*); he wrote that it “*doeth represent the square of squares squaredly*“.

At the time Recorde proposed this notation, there was no easy way of denoting the powers of numbers other than squares and cubes. The root word for Recorde’s notation is **zenzic**, which is a German spelling of the medieval Italian word *censo*, meaning “squared”. Since the square of a square of a number is its fourth power, Recorde used the word **zenzizenzic** (spelled by him as *zenzizenzike*) to express it. Some of the terms had prior use in Latin “zenzicubicus”, “zensizensicus” and “zensizenzum”. This is a condensed form of the Italian *censo di censo*, used by Leonardo of Pisa in his famous book *Liber Abaci* of 1202. Similarly, as the sixth power of a number is equal to the square of its cube, Recorde used the word *zenzicubike* to express it; a more modern spelling, **zenzicube**, is found in Samuel Jeake’s *Logisticelogia*. Finally, the word *zenzizenzizenzic* denotes the square of the square of a number’s square, which is its eighth power: in modern notation,

Recorde proposed three mathematical terms by which any power (that is, index or exponent) greater than 1 could be expressed: *zenzic*, i.e. squared; *cubic*; and *sursolid*, i.e. raised to a prime number greater than three, the smallest of which is five. Sursolids were as follows: 5 was the first; 7, the second; 11, the third; 13, the fourth; etc.

Therefore, a number raised to the power of six would be *zenzicubic*, a number raised to the power of seven would be the second sursolid, hence *bissursolid* (not a multiple of two and three), a number raised to the twelfth power would be the “zenzizenzicubic” and a number raised to the power of ten would be *the square of the (first) sursolid*. The fourteenth power was the square of the second sursolid, and the twenty-second was the square of the third sursolid.

The word, as well as the system, is obsolete except as a curiosity; the Oxford English Dictionary has only one citation for it. As well as being a mathematical oddity, it survives as a linguistic oddity: *zenzizenzizenzic* has more Zs than any other word in the OED.^{}^{
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Samuel Jeake, however, gives *zenzizenzizenzizenzike* (the square of the square of the square of the square) in a table in *A compleat body of arithmetic…*^{
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