Welcome to the Online Dictionary of Crystallography (the ODC) maintained by the Commission for Crystallographic Nomenclature (CCN) of the International Union of Crystallography (IUCr). The ODC functions as a virtual hyperglossary for journals published by the IUCr; when an article from one of the IUCr journals is read online the words defined in the ODC appear as clickable links. The ODC was envis