'Coolth' makes a comeback

When a friend showed up without me at one of our usual hangouts the other week, it was remarked that she was therefore "ruthless."

We had a chuckle over it but it sparked a discussion: Why do some words seem to be used only in the negative? Dictionaries do list ruthful, but how often do you hear it in conversation? Or see it in print?

It's derived from ruth as a common noun, meaning compassion for the misery of another. A second meaning is sorrow for one's own faults, or remorse.

All of which is enough to make me point out that although scholars are divided on the exact etymology of "Ruth" as a given name, I've found no source that traces it to the common noun.

Listless is another one of these odd socks. And it does not refer to the way you feel when you get to the supermarket and realize you have left your shopping list on the kitchen counter. ("I can just picture it there where I must have left it! Now if only I can make out whether it had 'balsamic vinegar' on it!")

No, the list you're lacking in this sense is desire. "The wind bloweth where it listeth." The wind blows where it wants to, we might say today. List is a relative of lust, which originally meant simply desire but has so narrowed that it really can't be used nowadays except to describe desires of the baser sort.

We speak of a damaged ship as "listing" – leaning before it keels over and sinks. This usage, too, seems to be linked to the idea that the ship tilts in the direction it "desires" to go – as if, with its hull punctured by a torpedo, it has any choice in the matter.

Unwittingly is another word we meet more often than its positive counterpart: "Unfamiliar with the security system in his brother-in-law's house, he opened a window in the guest room and unwittingly set off an alarm." Built on the archaic verb wit, meaning "to know," unwittingly is often used to signal lack of intent.

But when, in the public square, we need to be sure we're not talking about just joking around, we tend to go to the more direct and modern "knowingly." I've just done a Google News check: knowingly, 5,510 hits; wittingly, 72.

The most interesting "wittingly" I found was biblical: Jacob "guiding his hands wittingly" as he blessed Joseph's sons, giving the younger Ephraim the blessing that might have been expected to go to first-born Manasseh. "The old man knew what he was doing" is the clear implication.

Couth and kempt are a couple of words people sometimes throw around for laughs. Couth, though, seems to be a back formation – a word formed by removing elements from already existing longer words. Kempt, on the other hand, seems to be an actual archaic word, derived from the idea of "well-combed."

It turns out there's a word for this kind of thing – well, sort of: azygous, a term usually used in the natural sciences to refer to elements such as leaves or veins that are "unpaired," or as the Oxford English Dictionary quaintly puts it, "fellowless."

Coolth, as a counterpart to "warmth," is another word I wanted to check out after my initial "ruthless" discussion. I'd read that the Elizabethans had coolth, but that it had fallen out of the language since. After a bit of research, I've confirmed that earlier coolth, but also found that the word has made a modest comeback in our own day.

Some of them appear in earnest scientific papers; others in blogs whose authors aren't sure it's a real word. Usually coolth is used to mean literal temperature; once in a while it's used to mean "state of coolness," in the "hey, man, cool!" sense of the word.

Coolth, it seems, liveth.

• This weekly column appears with links at http://weblogs.csmonitor.com/verbal_energy.