A monomial is an expression in algebra that contains one term, like 3xy. Monomials include: numbers, whole numbers and variables that are multiplied together, and variables that are multiplied together. Any number, all by itself, is a monomial, like 5 or 2700. A monomial can also be a variable, like m or b. It can also be a combination of these, like 98b or 7rxyz.
There are two rules to remember about monomials:
2 * 2 = 4 (a monomial)
2 * x = 2x
2 * 6 = 12
2 * y = 2y
A monomial is an algebraic expression with only one term, so x * y or 47x + 2 are not monomials. All algebraic expressions with one term, however, are examples of monomials - so there are countless examples that encompass the entire number system.