Freemartin is a term used to describe a sterile female calf that is born from a twin pregnancy with a male calf. There are several synonyms for freemartin, including cull heifer, barren heifer, and spayed heifer. Other terms used to describe this condition include "dud" heifer, which refers to the animal's inability to breed, and "false twin," which refers to the animal's mixed gender. Additional synonyms for freemartin include neuters and steeroids. While these terms are often used interchangeably, they all refer to female calves who are unable to reproduce due to their mixed gender and hormonal imbalances.