An element 
of a ring is nilpotent if 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 Web Resource. https://mathworld.wolfram.com/NilpotentElement.html