Annexation is the act — or the finished event — of annexing: taking land and adding it to another country. Annex is the verb (and sometimes the extra building); annexation is the name of the move. News and history books use it like a legal stamp: “the annexation of X.” It sounds formal and clean, even when the taking was messy or violent. Though actually, not every annexation looks like an army walking in on one morning. Some are sudden; some are prepared for years with maps, papers, and new rules. Students sometimes use annexation for any war, or for any time an army stays in a place. An army can stay for a while and still call the place someone else’s. Annexation is when the taker treats the place as part of its own country from then on.