This course is intended to introduce the linguistic graduate student to the formal distinctions among basic ontological categories, such as objects, events, qualities, and their interplay with the lexicon. These categories will be characterized in an axiomatic way, which has been designed to provide some formal ontological ground to natural language applications. Finally, we shall also show possible ways to use the lexically-driven ontologies as a basis for deeper understanding of both human cognition and computer processing of natural languages.