Eponym comes from the Greek word eponumos meaning the giving of one's name to a thing or person. Typically an eponym comes from the name of a person, such as America or algorithm, but occasionally it can be from a brand name that has come to be used generically, such as escalator or spam. The following is a list of some of them, and how they came into being.
Algorithm - Abu Ja'far Mohammed ibn-Musa al-Khwarizmi was an Arab, probably from what is now Southern Uzbekistan, who taught at the Caliph's Palace of Wisdom in Baghdad in the 9th Century, and is one the most important mathematicians in history. Through Latin translations of his work, al-Khwarizmi introduced to Europe the Hindu-Arabic base 10 numerals - the use of which came to be known as algorism in English. He is also considered the 'inventor' of both zero and the decimal point, as well as devising algebra (the word algebra itself comes from the phrase al-jabr used in the title of one of his texts). The term algorism is still used in its original sense, although not widely, while its variant spelling algorithm fell out of use only to re-emerge in the 1930s with its current meaning, a sequential procedure to solve a mathematical problem.
Ammonia - Nitrogen hydride gas derives its name from the Egyptian fertility god Amun (also spelled Amen or Ammon). While retrospectively appropriate, ammonia being a prime constituent of most fertilizers, this is purely co-incidence: the ammonium chloride deposits collected from near the Temple of Jupiter Amun in Ancient Libya were given the name 'sal ammoniacus' (salt of Amun) by the Romans merely because of the temple's proximity, although the reason the deposits came to be there in the first place was through the copious quantities of dung and urine visitors' camels left as they drank from the nearby oasis. Based on this Roman precedent, the Swedish chemist Torbern Olof Bergman gave nitrogen hydride its current name in 1782. Amun also gave his name to the fossils known as ammonites, as he was usually depicted as having a ram's head, and the fossils were thought to resemble his horns.
Caesarian - The caesarian section is popularly thought to get its name from the manner of Caius Julius Caesar's birth. In fact, the reverse is true: the name Caesar comes from the Latin phrase 'a caeso matris utere' (from the cut womb of the mother), so technically caesarian is not an eponym.
Gerrymander - In 1812 Governor Eldridge Gerry of Massachussets revised local Congressional boundaries so as to prevent his fellow Democrats from suffering an ignominous defeat. The painter Gilbert Stuart saw a map of the area in question while working at the Boston Centinel newspaer, declared it to resemble a salamander, and promptly augmented it with wings, claws and a beak to create a cartoon. His editor, Benjamin Russell, decided that Gerry-mander was a more appropriate name for it, and the word almost immediately became the popular term for any unfair adjustment of electoral boundaries, as the Gerry-mander cartoon was subsequently copied extensively in political literature. Stuart's other, greater claim to fame is as the painter of George Washington's portrait as used on the one dollar bill, and Gerry emerged from the scandal relatively unscathed, going on to be James Madison's Vice-President.
Guillotine - Dr Joseph Ignace Guillotin was a penal reformer and member of the French Assembly in Revolutionary France. While he did not actually invent the guillotine - decapitation devices such as the Halifax Gibbet had been around since at least 1307 and were used as far afield as Persia - he was the first to advocate its use as a standard form of execution. Prior to the revolution the manner of capital punishment varied considerably both in efficiency and brutality, depending on social status and regional customs. Guillotin first proposed standardized decapitation in 1789 as one of six articles to be incorporated into the new penal code to promote a more egalitarian approach to capital justice. His proposals were repeatedly rejected, but were eventually accepted in 1791 (although Guillotin himself no longer favoured the death penalty) as the Assembly became increasingly aware of the logistical difficulties created by the spiralling numbers of executions required. Dr Antoine Louis was subsequently commissioned to design the machine, briefly known as the Louisette after it went into service in 1792, but it soon came to be known by Guillotin's name, despite him having disowned it.
Maverick - Samuel Augustus Maverick was a lawyer and land-owner in 19th Century America, famed as a signatory of the Texas Declaration of Independence and Mayor of San Antonio. His name originally came to be applied to unbranded cattle, and subsequently to any independently-minded or care-free person. The romanticized version of how this came to be is that he won a herd of cattle in a poker game and then let them roam unbranded across Southern Texas – a risky thing to do when they could freely mix with other herds, and unmarked cattle were effectively the property of whoever got their hot iron onto them first. In fact the cattle in question are likely to have been acquired somewhat reluctantly in payment for a more prosaic debt, or else simply bought by him. They were indeed unbranded, however this was not a great risk as his ranch was the only one on Matagorda Peninsula, and so the cattle had nowhere to go. His grandson Congressman Maury Maverick kept up the family tradition by coining the word gobbledygook in 1944.