characteristic equation
/karɪktəˌrɪstɪk ɪˈkweɪʒn/noun
1 Mathematics. More fully Gaussor Gauss's characteristic equation. An equation expressing the curvature of a surface in terms of certain parameters of the surface.
2 Mathematics. A quadratic equation in which the derivatives in a second order differential equation are replaced by scalar variables, obtained to facilitate the solution of the differential equation.
3 Mathematics. Any equation that in some way characterizes or summarizes something.
4 Physics. An equation relating the temperature, pressure, and volume of a gas; specifically the equation PV = RT.
5 Mathematics. An equation in which the characteristic polynomial of a particular matrix is equated to zero, which when solved gives the eigenvalues (latent roots) of the matrix.
Origin
Early 19th century; earliest use found in Philosophical Magazine. From characteristic + equation.