Nowadays the utility of multi-viewpoint approach is widely acknowledged in many areas, such as ontologies domain. The two concepts ontology and viewpoint are complementary, indeed the ontology represents the knowledge shared by multiple users and the viewpoint represents the domain knowledge that is relevant at a given viewpoint. With the coupling of these tow notions, we are talking about multi-viewpoints ontology. Multi-viewpoints ontology gives the same universe of discourse several partial descriptions such that each one is on a particular viewpoint. Due to the decentralized nature of the Web, there always exist multiple multi-viewpoints ontologies for overlapped domains and even for the same domain. Therefore, multi-viewpoints ontology alignment, is necessary to establish interoperation between Web application using different multi-veiwpoints ontologies. In this paper, we approach the problem of aligning multi-viewpoints ontologies. We focus firstly on the definition of multi-viewpoints ontology in description logics extended by a stamping mechanism. Then, we introduce the notion of multi-viewpoints in the alignment process.