The Pits

It's really easy to assume that if a word appears to be divisible into two sub-words, then each of those words must have its logical meaning. "Chilblain", for example, which means "an inflammation of the extremities caused by cold and moisture", is composed of "chill" and "blain", a sore or swelling, just as you would expect. But sometimes this will lead you astray, which, of course, is par for the course in English.

In this Boingboing article appears the following sentence:

If you want to believe that science, truth, and knowledge can save us from drowning in our own cess, these books will give you hope.

Well, that seems perfectly sensible, doesn't it? "Cesspool" or "cesspit" mean "a receptacle for sewage", so "cess" must logically mean "sewage; filth". Except it doesn't.

The "cess-" actually comes from "recess", which in this context means "a place to which one retires", fairly obviously referring to a water-closet or other privy.

When "cess" is used as a standalone word in English, it means something very different: abstracted from "assess", it means "tax or assessment". (The OED says that "sess" is the preferred spelling, based on etymology, but grudgingly concedes that the "cess" spelling is established.) The word has never had any currency in North America.