define teratogen
Definition of Teratogen. Basically, a teratogen is an agent that, once in contact with a pregnant mother, will produce a defect in the developing fetus. A teratogen can be either a physical substance or a condition in the mother. The resulting defect can be either a physical abnormality or a functional defect. With this general definition in mind, it's obvious that types of teratogens and their resulting issues can run the gamut.