- the act or an instance of annexing, or adding to something larger, especially the incorporation of new territory into the domain of a city, country, or state.
- the fact of being annexed: Annexation of the two parts of the Bronx in 1874 and 1895 gave New York City the last of its five boroughs.
- something annexed: Victory in battle resulted in territorial annexations that remained difficult to govern.
- the act of annexing, esp territory, or the condition of being annexed
- something annexed
1620s, from Medieval Latin annexiationem (nominative annexatio) “action of annexing,” noun of action from past participle stem of annexare (see annex). The Middle English noun form was annexion “union; joining; territory acquired” (mid-15c.).