1. uncountable noun [with poss] Accession is the act of taking up a position as the ruler of a country. [formal] [+ to] ⇒ ...the 50th anniversary of the Queen's accession to the throne. 2. uncountable noun [oft with poss, N to n] A country's accession to a group of countries or to an association is its joining that group of countries or association. [formal] ⇒ ...Namibia's accession to the Lome convention. ⇒ ...a ballot over the issue of Kashmir's accession to India.
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