The development of artificial intelligence began with ontology in the 1980s. Ontology, understood philosophically, is the science of beings. It is the attempt to represent reality in conceptual units. Today, artificial intelligence is developing rapidly, not ontologically, but as Large Language Models (LLMs), with the limitations and anomalies that arise. TerminusAI Legal Chat demonstrates what happens when legal ontology and LLM are combined. The result is an LLM that thinks like a lawyer, reasons decisions like a lawyer, and creates documents like a lawyer. In short, TerminusAI Legal Chat is AI with a legal brain.