— accessional , adj.
/ak sesh"euhn/ , n.
1. the act of coming into the possession of a right, title, office, etc.: accession to the throne.
2. an increase by something added: an accession of territory.
3. something added: a list of accessions to the college library.
4. Law. addition to property by growth or improvement.
5. consent; agreement; approval: accession to a demand.
6. Internat. Law. formal acceptance of a treaty, international convention, or other agreement between states.
7. the act of coming near; approach.
8. an attack or onset, as of a disease.
v.t.
9. to make a record of (a book, painting, etc.) in the order of acquisition.
10. to acquire (a book, painting, etc.), esp. for a permanent collection.
[ 1580-90; accession- (s. of accessio ) an approach, addition. See ACCESS, -ION ]