Nilpotent
In mathematics, an element x {\displaystyle x} of a ring R {\displaystyle R} is called nilpotent if there exists some positive integer n {\displaystyle n} such that x n = 0 {\displaystyle x^{n}=0} . The smallest such n {\displaystyle n} is called the index of nilpotency or the degree of nilpotency of x {\displaystyle x} .