The F- word

Michael Quinion's weekly World Wide Words newsletter pops into my email inbox every Saturday. It usually includes a Q&A. As Quinion explains in the newsletter for 30 April 2005, he had to obfuscate in order that not every ISP on the planet bounce the email. Hence "F- word".

Question: I remember someone telling me once, long ago, that actually the F-word is an abbreviation. The last two letters of the word were, I believe, contracted from the words "Carnal Knowledge". Could you help me out here, perhaps with some additional etymological data? [Heres Snijder, Canada]

Quinion's knowledgeable and unexpurgated account will be here in a few hours. His newsletter goes out some hours in advance of the website's update. [Update: wrong, wrong, wrong. I checked his website and it says in small print somewhere: later in the week]. While you wait, you can always look at back issues, and subscribe to the newsletter.