Castration is the removal of the testicles. In horses the operation is called gelding. It was used in medicine to treat some serious forms of prostate cancer by removing all possible sources of testosterone, which may stimulate the cancer.
This mutilating operation was performed on choirboys until a century ago to prevent their voice breaking and thus ruining their career. The “castrati” were admired as the best singers in the world for centuries.
Castration was also used in many societies, but particularly those of the Middle East, to create eunuchs who would protect their masters and particularly their women in the harem, but without being able to get them pregnant.
Slaves were sometimes castrated to make them more docile.
Castration was prohibited by the Hippocratic Oath, not because it was unethical, but because it was felt to be beneath the skills of a well-trained physician. The appropriate section of the oath can be translated as: “To preserve pure and immaculate my life and art, not to castrate even that may ask me to, but to leave this to manual labourers”.
Some members of the British aristocracy believed until late last century that hemi-castration (removal of one testicle) would give them male heirs, as sperm from the right testicle was meant to produce sons, sperm from the left daughters.