What's the Opposite of Warmth?

Coolth. That's right, it's a real word. Ruth Walker noted its resurgence as a scientific term in her language column in the Christian Science Monitor.

The Online Etymology Dictionary says it's been around for centuries: "Coolth, on model of warmth, is occasionally attested since 1547, and was used by Pound, Tolkien, Kipling, etc."

Beware, though -- the Columbia Guide to Standard American English calls its use "tiresomely jocular."

It makes me think of another tiresomely jocular term one might hear from the same sort of speaker: negatory. Meaning "no." I use it a lot when I gab on my citizens' band radio. Wikipedia speculates that its origin may be military.