The supergolden ratio ψ is the name given to the unique (and positive) real root ψ of the cubic equation x^3 = x^2 + 1. Its name derives from the fact that it is defined analogously the the usual golden ratio ϕ, but using the above cubic equation instead of the quadratic equation x^2 = x + 1 that defines ϕ.

golden ratio | Narayana cow sequence | Pisot number