1. the act of adding or attaching territory to an existing political unit such as a country, state, or city
2. the act of taking or adding something, especially without permission

Examples

• The annexation of Texas by the United States occurred in 1845.
• Many residents opposed the city’s annexation of their neighborhood.
• The annexation of the small country caused international controversy.
• The treaty formalized the annexation of the disputed territory.
• Citizens voted against the proposed annexation by the larger municipality.
• The annexation process required approval from both governments.