Abnormal development of a body part during the life of the embryo or fetus, usually but not always apparent at or soon after birth. It can be genetically inherited or be acquired by exposure to a physical or chemical insult, such as the action of a teratogen (a drug or other substance in the environment), during development in the mother's uterus. Few congenital abnormalities can be associated with a specific cause, and an apparent cause might not be the true one.

A congenital abnormality in males in which the urethra does not reach the tip of the penis, but opens near its base. The penis is usually short and curved, which can make sex difficult and can contribute to infertility.