"act of coming to a position," especially of a throne, 1640s, from Latin accessionem (nominative accessio) "a going to, joining, increase," noun of action from past participle stem of accedere "approach, enter upon" (see accede).
1. the accession of Queen Victoria to the throne
2. the silver jubilee of the Queen's accession
3. His accession to the important post was a big event.
4. He inherited vast estates on his accession to the throne.
5. On his accession to the throne, he inherited vast estates.