To annex something means to take control of and add an area or region to a larger country, state, or entity, often by force or without permission. It involves incorporating a territory or place into one's own domain, expanding the size or reach of that entity. For example, the United States annexed Texas in 1845, meaning Texas became part of the United States' territory.
Annexation can also refer to attaching or adding something as an extension or addition, such as annexing a building to a larger structure or annexing a document to a contract or report.
In summary, to annex something primarily means to take possession or control of a territory, but it can also mean to add or append something to a larger or more important entity.
