\begin{definition}[Definition:Quintic Equation]
Let $\map f x = a x^5 + b x^4 + c x^3 + d x^2 + e x + f$ be a polynomial function over a field $\mathbb k$ of degree $5$.
Then the equation $\map f x = 0$ is the general '''quintic equation''' over $\mathbb k$.
\end{definition}