n. & v.
--n.
1. entering upon an office (esp. the throne) or a condition (as manhood).
2 (often foll. by to) a thing added (e.g. a book to a library); increase, addition.
3 Law the incorporation of one item of property in another.
4 assent; the formal acceptance of a treaty etc.
--v.tr. record the addition of (a new item) to a library or museum.
Etymology: F accession or L accessio -onis (as ACCEDE)