ac·ces·sion 
(ăk-sĕshən)
(ăk-sĕshən)n.
1. The attainment of a dignity or rank: the queen's accession to the throne.
2.
a. Something that has been acquired or added; an acquisition.
b. An increase by means of something added.
3. Law
a. The addition to or increase in value of property by means of improvements or natural growth.
b. The right of a proprietor to ownership of such addition or increase.
4. Agreement or assent.
5. Access; admittance.
6. A sudden outburst.
tr.v. ac·ces·sioned, ac·ces·sion·ing, ac·ces·sions
To record in the order of acquisition: a curator accessioning newly acquired paintings.
ac·cession·al adj.