Noun | 1. | ![]() reptile genus - a genus of reptiles Crotalidae, family Crotalidae - New World vipers: pit vipers Agkistrodon contortrix, copperhead - common coppery brown pit viper of upland eastern United States Agkistrodon piscivorus, cottonmouth, cottonmouth moccasin, water moccasin - venomous semiaquatic snake of swamps in southern United States |