A Fixed Point for which the Stability Matrix has one zero Eigenvector with Negative Eigenvalue .
See also Elliptic Fixed Point (Differential Equations), Fixed Point, Hyperbolic Fixed Point (Differential Equations), Stable Improper Node, Stable Node, Stable Spiral Point, Unstable Improper Node, Unstable Node, Unstable Spiral Point, Unstable Star
References
Tabor, M. ``Classification of Fixed Points.'' §1.4.b in
Chaos and Integrability in Nonlinear Dynamics: An Introduction. New York: Wiley, pp. 22-25, 1989.