accession in WordNet English dictionary

1. the right to enter
   entree  access  accession  admission  admittance 
   
2. the act of attaining or gaining access to a new office or right or position (especially the throne)
   "Elizabeth's accession in 1558"
   accession  rise to power 
   
3. agreeing with or consenting to (often unwillingly)
   "accession to such demands would set a dangerous precedent"; "assenting to the Congressional determination"
   accession  assenting 
   
4. something added to what you already have
   "the librarian shelved the new accessions"; "he was a new addition to the staff"
   accession  addition 
   
5. (civil law) the right to all of that which your property produces whether by growth or improvement
   accession 
   
6. a process of increasing by addition (as to a collection or group)
   "the art collection grew through accession"
   accession 
   

1. make a record of additions to a collection, such as a library
   accession