The story
Named after Camille Jordan.
Etymology from Wiktionary, CC BY-SA 4.0.
Jordan block
Today it means: A Jordan block over a ring R (whose identities are the zero 0 and one 1) is a matrix composed of 0 elements everywhere except for the diagonal, which is filled with a fixed element λ ∈ R, and the superdiagonal, which is composed of ones. Full definition →