A nilpotent element is an element 
of a ring for which there exists
a positive integer 
for which 
.
Nilpotent Element
See also
Engel's TheoremExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Nilpotent Element." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/NilpotentElement.html