Software measurement, as a young discipline, suffers from the symptoms of any unconsolidated discipline. Unfortunately, there does not yet exist a consensus about the terminology used in this field. Therefore, the first step towards software measurement become a well established engineering discipline is to get a common agreement among software measurement researchers and practitioners about the concepts used in software measurement and the relationships between them. To reach this goal, it is well-known the usage of ontologies, due to an ontology represents a certain view of an application domain in which the concepts that live in this domain are defined in an unambiguous and explicit way. So that, the aim of this is to present a preliminary, practical and semi-formal ontology for software measurement.