Christoffel symbol

Short definition from Wiktionary

Noun

1. 1
   For a surface with parametrization ⃑x(u,v), and letting i,j,k∈u,v, the Christoffel symbol Γᵢⱼᵏ is the component of the second derivative ⃑x_ij in the direction of the first derivative ⃑x_k, and it encodes information about the surface's curvature. Thus,