A ridgling, or rig, is a cryptorchid; a male animal with one or both testicles undescended, usually describing a ram, bull, or male horse, but cryptorchidism also can be an issue in dogs and cats. Because the heat inside the body is too high for sperm to survive, an undescended testicle is non-functional. The condition is most often discussed in the horse world, as the health and behavioral issues surrounding adult males with the condition are of concern to owners and handlers of such animals.

A gelding is a castrated male horse or other equine, such as a pony, donkey or a mule. The term is also used with certain other animals and livestock, such as domesticated camels. By comparison, the equivalent term for a castrated male bull would be ox, or a wether for rams and billy goats.