accession vs accede

accession is a noun but accede is not a noun.

Word	Noun	Adjective	Verb	Adverb
accession	Yes	No	Yes	No
accede	No	No	Yes	No

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

accession (verb)	accede (verb)
make a record of additions to a collection, such as a library	yield to another's wish or opinion
	to agree or express agreement
	take on duties or office