In English, "poly-" is a prefix that means "many." Polynomials are groups of monomials that have been added or subtracted. Monomials are things like 3x, 4y, and the number 5. All of the monomials are called "terms of a polynomial."
Some polynomials have two terms and are called binomials. An example of a binomial is 5x - 2.
Some polynomials have three terms and are called trinomials. An example of trinomial is 9x2 + 6x + 1.