ADDER, a name for the common viper (Vipera berm) of Europe and Asia. The puff-adder (Bitis arietans), widespread in Africa, and the death-adder (Acanthophis antarcticus), of Aus tralia, are both very poisonous. In North America the harmless hognose snake (Heterodon contortrix), which hisses loudly, is called puffing adder or spreading adder. See HOGNOSE VIPERS.