1, monomial: the product of numbers and letters. Such algebraic expressions are called monomials. A single number or letter is also a monomial.

2. Coefficient of single item: numerical factor in single item.

3. The number of monomials: the exponential sum of all the letters in the monomials.

4. Polynomial: The sum of several monomials is called polynomial.

5. Term and degree of polynomial: the monomial in polynomial is called the term of polynomial, and the degree of the highest term in polynomial is called the degree of polynomial. Please note that the degree of a polynomial is not the exponential sum of all the letters that make up the polynomial! ! !

Algebraic expression: monomials and polynomials are collectively called algebraic expressions. (Algebraic expressions with letters in denominator are not algebraic expressions)