ABSTRACT: Ontologies are used to formally describe domains of interest. As domains change over time, the ontologies have to be updated accordingly. We advocate the introduction of an Ontology Update Language that captures frequent domain changes and hence facilitates regular updates to be made in ontologies. We thoroughly discuss the general design choices for defining such a language and a corresponding update framework. Moreover, we propose a concrete language proposal based on SPARQL Update and provide a reference implementation of the framework.