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

Lai had planned to visit Eswatini from April 22 to 26 for the 40th anniversary of King Mswati III's accession and his 58th birthday.

From Barron's • May 5, 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

Demonstrators against the Georgian government's suspension of its European Union accession bid have complained of other symptoms too - shortness of breath, coughing, and vomiting that lasted for weeks.

From BBC • Nov. 30, 2025

The old-fashioned keeps of Arthur’s accession had given place to a gaiety of defence, now difficult to imagine.

From "The Once and Future King" by T. H. White

Related Words

• enlargement
• extension