(2) Polynomial An algebraic expression consisting of several monomials is called a polynomial.
③ Coefficient: The sum of the indices of all letters in a monomial is called its number.
④ Times: The sum of the indexes of all variables in a single item is called the times of this single item.
⑤ Term: Each monomial that constitutes a polynomial is called a polynomial term.
⑥ Degree of Polynomial: The degree of the term with the highest degree in a polynomial is called the degree of the polynomial.
⑦ Similar terms: In polynomials, terms with the same letters and the same index of the same letters are called similar terms.
⑧ Merging similar terms: Merging similar terms in polynomials into one term is called merging similar terms.