A, -5, 1x, 2XY are all monomials, but 0.5m+n is not.

A monomial is a formula that only contains multiplication, and a single letter or number is also a monomial.

This noun was translated into Chinese by Li, a mathematician in Qing Dynasty, according to the concept of the original word.

1, the single item only contains multiplication and power operation, but not addition and subtraction operation;

2. The monomial can include the operation of division by numbers, but it cannot include the operation of division by unknowns.

Polynomial:

multinomial

A formula consisting of the algebraic sum of several monomials. Each monomial in a polynomial is called a polynomial term, and the highest degree of these monomials is the degree of this polynomial. Items without letters are called constant items. Polynomials with only one independent variable are called univariate polynomials, and polynomials with two (or more) independent variables are called multivariate polynomials.