Here we go!! origins of the word F U C K!!
Although this sounds like the most Anglo-Saxon of all Anglo-Saxon words, the origin of the f-word meaning 'sexual intercourse' is actually rather obscure. There is a legend that the old name for the crime of rape was 'Forced Unlawful Carnal Knowledge', and part of the punishment was that an abbreviation of the crime would be branded on the perpetrators head. Hence, people with 'F. U. C. K.' on their head were known to be rapists. A similar story is that during the time of the plague when it was necessary to increase the population a royal injunction was issued telling the common folk to 'Fornicate Under Command of the King.' These, however, would appear to be acronyms intentionally spelling out an existing word rather than new creations themselves.
Eric Partridge, a famous etymologist, has suggested that the Old German 'ficken' or 'fucken', meaning 'to strike or penetrate', was related to the Latin words for pugilist, puncture, and prick, or to the Latin 'futuere' which had the slang meaning 'to copulate'. There are also clearer links to Dutch where 'fokken' means breed and is applied to cattle, and to a Swedish dialect word 'fokken' which has the English meaning. Certainly, all the earliest uses of the word in English came via Scotland, suggesting a Scandinavian origin4.
Records from as early as 1278 identify a man called John Le-Fucker (which, considering people often had names to do with their occupations, makes the mind boggle), and it was certainly in common usage by the 16th Century, appearing in a dictionary, John Florio's A World of Words, in 1598. By the 18th century, it had became a vulgar term; It was even banned from the Oxford English Dictionary.