The highest power in a univariate polynomial is known as its degree, or sometimes "order." For example, the polynomial

is of degree , denoted . The (structural) degree of a polynomial is implemented in the Wolfram Language as Exponent[poly, x]. Richardson's theorem proves that it is recursively undecidable to determine the degree of an arbitrary polynomial.

More things to try:

Weisstein, Eric W. "Polynomial Degree." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/PolynomialDegree.html