Also Clay, that locknut is used to, I was told set the head spacing for the rifle.    From Wordnik.com.  [Savagery in South Dakota] Reference

I call it the “syncopated pedaling creak,” usually a sign that the locknut on a campy cassette is not tight enough.    From Wordnik.com.  [Technical FAQ with Lennard Zinn: Bike creaking solutions] Reference

The front hub features a 100mm locknut-to-locknut measurement, similar to a conventional quick release hub.    From Wordnik.com.  [Dirt Rag Online!] Reference

To loosen it, I had to lie underneath it (wearing eye protection as crud falls everywhere), pass my left hand up between the transfer box and chassis rail, pass my right hand over the chassis rail and under the floor, and then turn the locknut through a quarter turn at the time.    From Wordnik.com.  [Musings from a Stonehead] Reference

There are other silent letters, such as the "g" in "gn", the "k" in "kn", and the "w" in "wr", when the relevant letter-combinations occur at the beginning of words, as in gnaw and gnome but not in cygnet and cognomen; in knife and knot but not in locknut; and in wretch and wrong but not in awry.    From Wordnik.com.  [Lingering over lingerie?] Reference