Polyatomic molecules contain: more than two atoms of the same or different type. two of the same types of atoms. two different types of atoms. only two atoms of the same or different type.

We are tasked to find the appropriate definition of a Polyatomic. Polyatomic molecules are molecules that contain more than two atoms of different or the same type. This comes from the Greek word Poly means many. Thus, the answer to the question above is the first choice.