A takeover of a government. It's usually associated with guns and tanks - a military coup. But the word can be used to describe bloodless coups - again the troops may be involved, with the threat of blood being sufficient to force a change in rule. There can be bloodless sans military, with the culprit being the CIA, the Trilateral Commission, the Cracking Horde sh0kk tr00pz of the Geek Revolution, or the space aliens who've taken control of our minds. Maman! Me need hug.