Administrative processes are a type of business process commonly used in public institutions and large companies. The workflow definitions of these processes are frequently reused within the organizations. The reuse of these workflow definitions can be easier if they are divided into three separate but related definitions: on the one hand, the definition of the data structures to be managed by the process activities, on the other, the users that can perform each activity and, finally, the process activities together with the relationships among the three definitions. The use of ontologies can facilitate these workflow definitions in the three related parts. In this paper, we describe OntoMetaWorkflow, a generic ontology to represent canonical workflow terms in the domain of administrative processes, and the methods for using it in defining administrative processes. This ontology is the basis of the WEAPON Model, a complete model supported by tools, for defining and managing administrative process workflows.