What is a Mononomial - Algebra I

Expression Definition: A mathematical phrase that has terms that can be constants, variables, operators and exponents.
Lets say we have expression
100+x-3xy+y/3+9x^2y^3


Monomial: A single term that can be
A Real number such as 2,-3, 100,2.5,2/3
A Variable such as x,y,z
A product of Real number and a variable or variables with whole number exponents
such as 4x,,4xy, 9x^2, 9xy^3, x/4

What is MonoNomial in Math - Algebra I