accession

American  

[ak-sesh-uhn] / ækˈsɛʃ ən /

noun

1. the act of coming into the possession of a right, title, office, etc..

   accession to the throne.

2. an increase by something added.

   an accession of territory.

3. something added.

   a list of accessions to the college library.

4. Law. addition to property by growth or improvement.

5. consent; agreement; approval.

   accession to a demand.

6. International Law. formal acceptance of a treaty, international convention, or other agreement between states.

7. the act of coming near; approach.

8. an attack or onset, as of a disease.

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verb (used with object)

1. to make a record of (a book, painting, etc.) in the order of acquisition.

2. to acquire (a book, painting, etc.), especially for a permanent collection.

accession British  

/ əkˈsɛʃən /

noun

1. the act of entering upon or attaining to an office, right, condition, etc

2. an increase due to an addition

3. an addition, as to a collection

4. property law

   1. an addition to land or property by natural increase or improvement

   2. the owner's right to the increased value of such land

5. international law the formal acceptance of a convention or treaty

6. agreement; consent

7. a less common word for access

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verb

1. (tr) to make a record of (additions to a collection)

Other Word Forms

• accessional
  adjective
• nonaccession
  noun
• reaccession
  noun
• unaccessional
  adjective

Etymology

Origin of accession

1580–90; < Latin accessiōn- (stem of accessiō ) an approach, addition. See access, -ion

Explanation

Accession is the act of advancing into a position. Being elected class president is a kind of accession. Accession originally referred to a queen or king taking the throne. From the Latin term, accessionem, meaning "joining or increasing,” accession may refer to the gaining of access to any formal position, group, or right. It can also mean “agreement” — think of it as “joining in.” Accession may also refer to property — either something that increases your original collection, or the right to all of your property even through growth — such as the golden egg your new hen laid.

Example Sentences

The Chinese share of U.S. imports has now fallen below where it stood before Beijing’s WTO accession 25 years ago.

From MarketWatch • May 14, 2026

"The end of Hungarian obstruction to Ukraine's accession does not mean it will accelerate," summed up Sebastien Maillard from the Jacques Delors think tank.

From Barron's • Apr. 13, 2026

With even weaker religious credentials than his father, Mr. Khamenei owes his accession to the hereditary principle despised by the 1979 revolution.

From The Wall Street Journal • Mar. 9, 2026

Bulgaria's accession will bring the number of Europeans using the euro to more than 350 million.

From Barron's • Dec. 31, 2025

A somewhat more immediate influence was Aristotle himself, whose death in 322 happened to coincide with Ptolemy’s accession to the governorship of Egypt.

From "Circumference" by Nicholas Nicastro

Related Words

• enlargement
• extension