Synonyms for accession

noun

• something added to what you already have
• agreeing with or consenting to (often unwillingly)
• the act of attaining or gaining access to a new office or right or position (especially the throne)
• the right to enter
• a process of increasing by addition (as to a collection or group)
• (civil law) the right to all of that which your property produces whether by growth or improvement

verb

• make a record of additions to a collection, such as a library