<p><strong>Noun</strong></p><ul><li>any of several venomous Old World snakes of the genus Vipera, especially V. berus, a small snake common in northern Eurasia</li><li>any related snakes belonging to the family Viperidae, characterized by erectile, venom-conducting fangs</li><li>pit viper</li><li>any of various venomous or supposedly venomous snakes</li><li>a malignant or spiteful person</li><li>a false or treacherous person</li><li>Viper, Military: a 9-pound (4-kilogram), shoulder-launched, unguided U.S. Army antitank rocket with an effective range of 273 yards (250 meters)</li></ul>