For effective information exchange in agent-based systems, domain-specific ontology is strongly needed, which is the vocabulary representing facts and relations of objects in the domain. In this paper, a semi-formal domain-specific ontology for shop floor focusing on Automated Guided Vehicle Systems (AGVS) is presented. The domain-specific ontology is developed on Protégé, a leading frame-based ontology editor, and is further converted into JADE™ (Java Agent DEvelopment Framework) compliant java classes. The developed ontology has been used in agent-communication of a simulator known as agent-based shop floor simulator (ABSFSim). Agent communication used in the ABSFSim is discussed. Agentbased simulation model of a sample manufacturing system is built with ABSFSim and the working of the model is verified and validated by comparing the output with an equivalent model developed in ProModel. The ontology development process presented in this paper is useful for developing agent-based models in different sections of manufacturing and also for developing high level agent-based software platforms for manufacturing systems.