I have searched the net for the origins of the world fuck and found several explanations. Some claim that word is acronymous for:
1. Fornication Under Consent of the King - tacked up over the doors of government-approved brothels in early England.
2. Fornication Under Consent of the King - same sentence, just describing old England whose population was decimated by plague and wars, and therefore fornification was highly desirable and encouraged by the King himself.
3. For Unlawful Carnal Knowledge - expression used by religious pilgrims in the early history of The American States (16th century). When somebody was caught and punished by their judge, sentence would said: “For unlawful carnal knowledge…” In a typical American way this phrase was shortened to “F.U.C.K.” and written on the court documents or used in the newspapers headline, such as “Mr.Smith found guilty in FUCK."
Fortunatelly nothing of this is true . The best possible guess is that "fuck" comes from the Middle English fucken,(to strike, move quickly, penetrate), from the German ficken, and the Dutch fokken, meaning almost the same thing. There are also claims that the F-word also has origins in the French foutre, which comes from the Latin futuere.