accession

Universal Words noun ~ (to sth) 1 [U] the act of becoming a ruler of a country: the accession of Queen Victoria to the throne seealsoACCEDE 2 [U] the act of becoming part of an international organization: the accession of new member states to the EU 3 [C] (technical) a thing that is added to a collection of objects, paintings, etc. in a library or museum