\begin{definition}[Definition:Constant Polynomial/Definition 3]
Let $R$ be a commutative ring with unity.
Let $P \in R \left[{x}\right]$ be a polynomial in one variable over $R$.
The polynomial $P$ is a '''constant polynomial''' {{iff}} it is in the image of the canonical embedding $R \to R \left[{x}\right]$.
\end{definition}