I couldn't find the other post relating to this so apologies for a double post. There are many claimed sources, but this sounds believable. Took this from a news group: "Earliest known appearance of the f-word: 1278, in a personal name (John le F*cker [where * = u]). I'm not making it up. The word is undoubtedly Germanic in origin; the earliest known examples are Scottish in origin, which suggests an earlier Scandinavian source (Scots Gaelic and Norn, the ancient language-base of the Scandinavia tongues, share a lot of similarities). The word probably migrated from Norwegian dialect (fukka or fokka; copulate), or Swedish dialect (focka; copulate or hit, alternately fock; penis). The last example fascinates me; already the word is becoming linguistic duct tape. Focka could mean both copulate (a nice thing) AND hit (a not nice thing), similar to many of its modern uses (f you does not imply romantic interest, after all). Also, fock is plainly derivative of focka, which in itself is pretty interesting. You know, English is only one of a handful of languages that has two words for a male chicken? Rooster is a comparatively late invention, intended to be an alternate for the other "vulgar" word."