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.
During the 1960s the term underground acquired a new meaning in that it referred to members of the so-called counterculture, i.e. those people who did not necessarily conform to the mainstream of human experience such as e.g. hippies, Punks, and Mods .
Terry Anderson describes the early 1970s high point of the utopia of counterculture in his book The Movement and The Sixties:
Applied to the arts, the term underground typically means artists that are not corporately sponsored and don't generally want to be.
Underground comics were a sizeable industry in the 1970s, part of the Underground press which included newspapers like International Times and magazines like Oz. The comicstrips by artists like Robert Crumb and Gilbert Shelton appeared both in the underground newspapers and as separate comic books and many of these latter are still being published today.
Underground can also mean that something is really groundbreaking and therefore is not mainstream.
Perhaps the best way to define it is a quote by Frank Zappa:
An alternate usage of the term "underground" is in reference to something that is illegal or so controversial that it would be dangerous for it to be publicized. Or it's so controversial (as in, offensive to societal norms) that it will never be mainstream. Some authors/artists use this as a badge of pride.
Examples:
An underground club might have illicit drugs readily available.
A movie is banned because people might imitate the actions of the characters.
In Economics, the term underground culture refers more or less to the parallel market (underground market) and the orthodox of the individuals who sell good and services and consume those goods and services.
eg. Prostitution markets or illegal drug trading