So that the software and web measurement field can become a more robust engineering discipline, it is mandatory to start reaching a common agreement between researchers and other stakeholders about primitive concepts such as attribute, metric, measure, measurement and calculation method, scale, elementary and global indicator, calculable concept, among others. There are various useful recently-issued ISO standards related to software quality models, measurement and evaluation processes, however, we observe sometimes a lack of a sound consensus among the same terms in different documents or sometimes absent terms. In this work we present an ontology for software metrics and indicators -based as much as possible on the concepts of those standards, which can be useful to support different assurance processes, methods and tools in addition to being the foundation for our cataloging web system [12]. Without sound and consensuated definitions it is difficult to assure metadata consistency and, ultimately, data values are comparable on the same basis.