Degree of a polynomial

The degree of a polynomial is the highest power of $x$ which appears in it. For example, the degree of $7-5x+4x^2$ is $2$, as the highest power of $x$ which appears is $x^2$. The degree of a constant polynomial (such as $7$) is zero, as the polynomial can be thought of as $7x^0$. The degree of the zero polynomial ($0$) is usually considered to be undefined.