Definition:Monic Polynomial

Definition
Let $A$ be a commutative ring with unity $1$.

Let $f = a_0 + a_1 X + \cdots + a_{r-1} X^{r-1} + a_r X^r$ be a polynomial in the single indeterminate $X$ over $A$.

Then $f$ is monic if the leading coefficient of $f$ is $1$.

Original Definition
Let $\displaystyle f = \sum_{k \mathop = 0}^n a_k \circ x^k$ be a polynomial in $x$ over $D$.

If the leading coefficient $a_n$ of $f$ is $1_R$, then $f$ is monic.