Booth offered this explanation of the term to the Medievalists blog: "I suggest it could either mean an actual attempt at copulation by an inexperienced youth, later reported by a rejected girlfriend, or an equivalent of the word ‘dimwit’ i.e. a man who might think that that was the correct way to go about it."
If so, it shifts back the rough historical consensus on when the word widely entered the vernacular as a vulgar, pejorative term. It's believed not to have existed in Old English -- the language of certain famous Anglo-Saxon sagas -- but to have crossed over the North Sea in the Middle Ages from lands around modern-day Holland and Germany.
The Oxford English Dictionary suggests that the "first definite evidence for the word, then, comes from a manuscript in Oxford (MS Brasenose College, Oxford VII), dated 1528."
Time magazine, in a 2008 explainer, offered this crash course in etymology:
First printed in a Scottish poem in 1503, the ancient and awesomely powerful F-bomb continues to mystify lexicographers. Rumors persist that legal acronyms spawned the obscenity in question ("Fornication Under Consent of the King" or the Irish police-blotter inscription "booked For Unlawful Carnal Knowledge"), though the modern-day phrase has been traced to a number of etymological origins: Middle Dutch (fokken), Germanic (ficken), English (firk), Scottish (fukkit). Even the Latin terms futuerre ("to copulate") and pungo ("to prick") bear a striking resemblance to the four-letter word. Of course, its original definition linking sex with violence and pleasure with pain has broadened considerably in the past 500 years.
Melissa Mohr, author of a book about the history of swearing, details an even earlier source, a late 15th century poem penned by Carmelite monks in the town of Ely. It's written in a mixed Latin-English code that rendered into a modern-day English would read: "They [the monks] are not in heaven, because they f*** the wives of Ely."
By a century later, Mohr notes, the f-bomb was everywhere.
F*** appears to have hit its stride by the late 16th century. In 1598, John Florio published an Italian-English dictionary intended to teach people these languages as they were really spoken. Florio's dictionary is thus full of f***s. He defines the Italian fottere as "to jape, to sard, to f***, to swive, to occupy," for example, while fottitrice is "a woman f***er, swiver, ... etc." and fottitore the male equivalent.
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