Ontologies can be used in Domain Oriented Software Engineering Environments (DOSEEs) to organize and describe knowledge and to support management, acquisition and sharing of knowledge regarding some domain. However, ontology construction is not a simple task. Thus, it is necessary to provide tools that support ontology development. This paper discusses the use of ontologies to support domain-oriented software development in ODE, an Ontology-based software Development Environment, and presents ODEd, an ontology editor developed to satisfy the requirements for an ontology editor in a DOSEE. These requirements include the definition of concepts and relations using graphic representations, automatic generation of some classes of axioms, derivation of object frameworks from ontologies, and ontology instantiation and browsing.