Answer
polynomial of degree 0.
Work Step by Step
Polynomials consist of one or more monomials and have the form:
$$a_nx^n+a_{n-1}x^{n-1}+...+ a_1x+a+0$$
where $x$ is the variable, $a_n$ is the leading coefficient, and $n$ is a non-negative integer called the degree.
We see that the expression $-\pi$ can be thought of as a polynomial with degree $0$ ($a=-\pi$ in the expression above).
