<unk> or<unk> is a surgical technique leaving a male or female unable to procreate. It is a method of birth control.  For non-surgical causes of sterility, see infertility.
Common<unk> methods include:
Vasectomy in males. The vasa deferentia, the tubes which connect the testicles to the prostate, are cut and closed. This prevents sperm produced in the testicles to enter the ejaculated semen (which is mostly produced in the seminal vesicles and prostate). Although the term vasectomy is established in the general community, the correct medical terminology is deferentectomy, since the structure known as the vas deferens has been renamed the ductus deferens.
Tubal ligation in females, known popularly as "having one's tubes tied". The Fallopian tubes, which allow the sperm to fertilize the ovum and would carry the fertilized ovum to the uterus, are closed. This generally involves a general anesthetic and a laparotomy or laparoscopic approach to cut, clip or cauterize the fallopian tubes. Less commonly used is the Essure office procedure of inducing scarring and occlusion of the tubes by the effects of micro-inserts placed by a catheter passed through the cervix and uterus.
Hysterectomy in females.  The uterus is surgically removed, permanently preventing pregnancy and some diseases, such as uterine cancer.
Castration in males.  The testicles are surgically removed. This is frequently used for the<unk> of animals, with added effects such as docility, greatly reduced sexual behavior, and faster weight gain (which is desirable in some cases, for example to accelerate meat production).
Sterilization 
Detoxification
Halogenation
Fermentation 
Electrolysis
Freeze drying
Urination
Induction heating