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.

---

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

---

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

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

When Iceland's accession negotiations were paused, 27 of the 33 chapters had been opened, and 11 had been concluded, according to the government.

From Barron's • Mar. 6, 2026

There can be little doubt of the struggle the King has had, balancing family loyalty, a situation he inherited upon accession, and his duty to the Crown.

From BBC • Feb. 19, 2026

By the accession of Leopold II in 1790, an empire based on a “feudal hierarchy of status” found itself in the age of Romantic nationalism, democracy and “enlightened ridicule.”

From The Wall Street Journal • Dec. 26, 2025

Emma spoke her pity so very kindly, that with a sudden accession of gay thought, he cried,

From "Emma" by Jane Austen

Related Words

• enlargement
• extension