<p><strong>Noun</strong></p><ul><li>the act of coming into the possession of a right, title, office, etc.: accession to the throne.</li><li>an increase by something added: an accession of territory.</li><li>something added: a list of accessions to the college library.</li><li>addition to property by growth or improvement.</li><li>consent; agreement; approval: accession to a demand.</li><li>formal acceptance of a treaty, international convention, or other agreement between states.</li><li>the act of coming near; approach.</li><li>an attack or onset, as of a disease.</li></ul><p><strong>Verb</strong></p><ul><li>to make a record of (a book, painting, etc.) in the order of acquisition.</li><li>to acquire (a book, painting, etc.), especially for a permanent collection.</li></ul>