The aim of this chapter is to apply Systems Theory – Systems Science – to Ontologies. The subject matter is given a modern context. The chapter contains a brief description of Systems Theory, which today has become what is known as Systems Science. Subsequently, Systems Science and systems are defined, as well as the links that are responsible for the correct function of a system, known as vectors. Ontologies will be discussed, along with their various definitions and characteristics. This chapter will be based on the premise that Ontology is a complex, conceptual, empirical classification system. An Ontology is structured like a system in which the principal and primary node is the word. A summary will be made of how this system should be constructed, concentrating on the vectors that help the system function. This will be illustrated with an example.