Viperids are a family of venomous snakes that include vipers, rattlesnakes, and pit vipers. There are several synonyms for viperids, such as viperine, viperan, and viperiform. Viperine refers to anything related to a viper or viperids family. Viperan is a more general term that refers to any animal or plant that resembles a viper. Viperiform, on the other hand, describes anything that is snake-shaped or resembles a snake. Other synonyms for viperids include serpents, ophidians, and adders. Whatever synonym is used, it is important to remember that viperids are dangerous and should be approached with caution.