ophidian, serpent, snake - limbless scaly elongate reptile; some are venomous

family Viperidae, Viperidae - Old World vipers

common viper, Vipera berus, adder - small terrestrial viper common in northern Eurasia

asp, asp viper, Vipera aspis - of southern Europe; similar to but smaller than the adder

Bitis arietans, puff adder - large African viper that inflates its body when alarmed

Bitis gabonica, gaboon viper - large heavy-bodied brilliantly marked and extremely venomous west African viper

cerastes, Cerastes cornutus, horned asp, horned viper, sand viper - highly venomous viper of northern Africa and southwestern Asia having a horny spine above each eye

pit viper - New World vipers with hollow fangs and a heat-sensitive pit on each side of the head