ˌWarsaw ˈPact, the BrE AmE ( also ˌWarsaw ˈTreaty Organiˌzation )
a group of countries in eastern Europe, including Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, and the former Soviet Union, which was established in 1955 to oppose ↑ NATO during the ↑ cold war .The Warsaw Pact ended in 1991 when most of the Communist governments of eastern Europe lost power.