  Under the historical definition of entanglement, namely that encountered in
Einstein--Podolski--Rosen (EPR)--type experiments, it is shown that a
particular Slater determinant is entangled. Thus a definition which holds that
any Slater determinant is unentangled, found in the literature, is inconsistent
with the historical definition. A generalization of the historical definition
that embodies its meaning as quantum correlation of observables, in the spirit
of the work of many others, but is much simpler and more physically
transparent, is presented.
