(Yes, "5" is a polynomial, ... Monomial, Binomial, Trinomial. There are special names for polynomials with 1, 2 or 3 terms: How do you remember the names?
The degree of a polynomial is the highest degree of its monomials with non-zero coefficients. The degree of a term is the sum of the exponents of the variables that appear in it. The term order has been used as a synonym of degree but, nowadays, may refer to several other concepts (see order of a polynomial).
Since the base is the same, we add the exponents to get 3 5x. Two players with the same base...that would never fly in baseball. Fortunately, in algebra, they can pile onto the same base as much as they like.
A polynomial as oppose to the monomial is a sum of monomials where each monomial is called a term. The degree of the polynomial is the greatest degree of its terms. A polynomial is usually written with the term with the highest exponent of the variable first and then decreasing from left to right.
You can also divide polynomials (but the result may not be a polynomial). Degree The degree of a polynomial with only one variable is the largest exponent of that variable.