Teratogenic is an adjective used to describe substances that cause birth defects in developing fetuses. There are several synonyms that can be used to describe the same condition. For instance, mutagenic is used for substances that alter or promote changes in the genetic material of an organism leading to variations in its offspring. Embryotoxic is used to describe substances that cause harm to developing embryos. Carcinogenic refers to substances that promote the formation of cancer cells while fetotoxic is used to describe substances that adversely affect the growing fetus. Hence, these synonyms have similar but distinct meanings that can be used interchangeably or depending on the context in which they are used.