If Hessian Matric H is zero at any point, then the point is called?

If Hessian Matric H is zero at any point, then the point is called?

Explanation
The Hessian matrix is used to determine the nature of critical points in multivariable calculus.
When the Hessian matrix H is zero, the second derivative test is inconclusive, and the point is classified as parabolic.