A polynomial is a math expression made up of two or more terms (you can identify the terms because they are separated by + or -)
The given expression has 2 terms (-c^5 and -bd). Then it is a polynomial.
To determine the type of polynomial count the number of terms; as the given polynomial has two terms it is a binomial.
The degree of a polynomial is the greatest exponent, for the given polynomial the degree is 5.
Then, the given expression is a polynomial; more specifically a binomial and its degree is 5