A point p on a regular surface M element R^3 is said to be parabolic if the Gaussian curvature K(p) = 0 but S(p)!=0 (where S is the shape operator), or equivalently, exactly one of the principal curvatures κ_1, κ_2 equals 0.

anticlastic | elliptic point | Gaussian curvature | hyperbolic point | planar point | synclastic