Open English Wordnet
Nouns
(n)accessiona process of increasing by addition (as to a collection or group)“the art collection grew through accession” (n)accession(civil law) the right to all of that which your property produces whether by growth or improvement (n)accession, additionsomething added to what you already have“the librarian shelved the new accessions”,
“he was a new addition to the staff” (n)accession, assentingagreeing with or consenting to (often unwillingly)“accession to such demands would set a dangerous precedent”,
“assenting to the Congressional determination” (n)accession, rise to powerthe act of attaining or gaining access to a new office or right or position (especially the throne)“Elizabeth's accession in 1558” Verbs
(v)accessionmake a record of additions to a collection, such as a library