Oophorectomy is the surgical removal of the ovaries of a female animal. In the case of non-human animals, this is also called spaying. It is a form of sterilization.
The removal of the ovaries together with the Fallopian tubes is called salpingo-oophorectomy. Oophorectomy and salpingo-oophorectomy are not common forms of birth control in humans; more usual is tubal ligation, in which the Fallopian tubes are blocked but the ovaries remain intact.
In humans, oophorectomy is most usually performed together with a hysterectomy - the removal of the uterus. Its use in a hysterectomy when there are no other health problems is somewhat controversial.
In animals, spaying involves an invasive removal of the ovaries, but rarely has major complications; the superstition that it causes weight gain is not based on fact. Spaying is especially important for certain animals that require the ovum to be released at a certain interval (called estrus or "heat"), such as cats and dogs. If the cell is not released during these animal's heat, it can cause severe medical problems that can be averted by spaying or partnering the animal with a male.
Oophorectomy is sometimes referred to as castration, but that term is most often used to mean the removal of a male animal's testicles.
The term adult describes any mature organism, but normally it refers to a human: one that is no longer a child and is now either a man or a woman. Coming of age is the event of becoming an adult, i.e. of entering adulthood.
Legally it means that one can engage in a contract. The same or a different minimum age may be applicable for e.g. parents losing parenting rights and duties regarding the person concerned, parents losing financial responsibility, marriage, voting, having a job, being a soldier, driving, travelling abroad, drinking alcoholic beverages (perhaps different ages for different categories), smoking, Censored page, being a Censored page (if legal at all), being a client of a prostitute, being a model or actor in pornography, etc.
The legal definition of entering adulthood varies between ages 16-21, depending on the region in question. Some cultures in Africa define adult at age 13, but most other civilizations consider this the teenager stage.
Often the age is 18. Exceptions:
"Adult" also means "not considered suitable for children", in particular as a euphemism for being related to Censored page, e.g. adult entertainment, adult video, adult magazine, adult bookstore.
However, adult education simply means education for adults, not particularly Censored page.