Unipotent

In mathematics, a unipotent element, r, of a ring, R, is one such that r − 1 is a nilpotent element; in other words, (r − 1) is zero for some n.

In particular, a square matrix, M, is a unipotent matrix, if and only if its characteristic polynomial, P(t), is a power of t − 1. Equivalently, M is unipotent if all its eigenvalues are 1.