Annexation
WordNet
noun
(1) The formal act of acquiring something (especially territory) by conquest or occupation
"The French annexation of Madagascar as a colony in 1896"
"A protectorate has frequently been a first step to annexation"
(2) Incorporation by joining or uniting
WiktionaryText
Noun
- the act of annexing, or territories that have been annexed
- the legal merging of a territory into another body