在数学里面，迭代幂次（亦作超-4运算），或可理解为迭代乘方、幂塔运算和超幂运算等等，是专指幂的下一个超运算级别，用以表示极大的数字。以下枚举了首四个超运算级别，其中迭代幂次为第四级，（后继函数，例如即将加上一，可理解为第零级运算，相关解释参见皮亚诺公理）。范例如下：

以上每一个运算级别皆被定义为对上一运算级别的迭代（迭代幂次的下一个运算级别为超-5运算）。迭代幂次跟首三个运算级别的一大不同之处在于首三个运算级别中的n 可以是任意复数，而n 为任意复数的迭代幂次目前则未有一个概括的定义。另外，迭代幂次不属于初等函数。

In mathematics, tetration (or hyper-4) is the next hyperoperation after exponentiation, and is defined as iterated exponentiation. The word was coined by Reuben Louis Goodstein, from tetra- (four) and iteration. Tetration is used for the notation of very large numbers. Shown here are the first four hyperoperations, with tetration as the fourth (and succession, the unary operation denoted taking and yielding the number after , as the 0th):