It's hard to imagine the English language without the word cool as a colloquial description of someone or something first-rate. Over the past half-century of usage, the word has become so omnipresent that it has lost much of its slangy patina. Slang-watcher Connie Eble noted here that when she asks her students at the University of North Carolina to list items of slang, they don't even think of cool, since "it's just ordinary vocabulary for them." How did cool first break through to the mainstream?

Because of the ubiquity of cool, it's easy to surmise that it has always been with us in its now-familiar form. When it comes to language, our minds usually work the other way: if we have encountered a word or phrase only recently, we tend to think that it must be new to everyone else, too. Stanford linguist Arnold Zwicky has called this the Recency Illusion. The flip side to the Recency Illusion is the Antiquity Illusion, when we assume relatively new expressions are much older than they actually are. A good example is "the whole nine yards," an idiom that has only been dated back to the early 1960s, despite various claims of a much earlier origin.

Cool fell victim to the Antiquity Illusion not too long ago in a lengthy debate on the letters page of The Times (UK) Literary Supplement. As I discuss in my "On Language" column in this Sunday's New York Times Magazine, the debate was sparked by a TLS reviewer who took a translator to task for using cool in its slangy sense, despite the book's setting in the 1930s. In my column I explain how the TLS letter writers misinterpreted older examples of cool with anachronistically modern readings.

Cool is an old word, of course, and leading up to the 20th century it had developed an array of meanings from "calm and dispassionate" to "audaciously impudent." But it took the jazzmen of the 1940s to transform it into the universal sign of approval that we know and love. The writer Zora Neale Hurston might have presaged the jazz world's adoption of the word when she used the phrase "whut make it so cool" several times in the mid-'30s, but it could be argued that she was still drawing on the older "audacious" meaning of cool.

In jazz circles, cool (as in "That's cool," "He's cool," or simply "Cool!") first came to be associated with sax player Lester "Pres" Young in the early '40s. The breakout year in terms of its appearance in mainstream publications came in 1948, when The New Yorker reported, "The bebop people have a language of their own... Their expressions of approval include 'cool'!" That same year, music critics picked up on the use of cool to describe a new, more relaxed style of jazz. "Hot jazz is dead. Long live cool jazz!" announced The Bridgeport Telegram, while Life profiled Dizzy Gillespie as a "trumpeter who is hot, cool and gone" (a description that must have baffled most of Life's readers at the time).

Cool's big crossover to white teenagers happened about four years later. A June 1952 article about teen slang in the St. Joseph, Michigan Herald-Press explained that "to be 'cool' is the desire of every teen-ager." It also turned up that year in a now-hilarious film called "Young Man's Fancy," sponsored by the Edison Electric Institute, which you can watch online here and here. The protagonist Judy, a slang-slinging teenybopper, calls her crush "really cool" — and even better, "a real cool Jonah." (Not for nothing did this film get the wise-cracking treatment from the cult favorite "Mystery Science Theater 3000.")

Cool has ebbed and flowed a bit over the years, losing some of its luster in the '60s before coming back on a wave of retro nostalgia in the '70s. (Think of Arthur Fonzarelli of "Happy Days" and Danny Zuko of "Grease" — those would-be Brandos — as the avatars of retro-cool.) By now it's become a permanent fixture in English around the world, continuing to spawn books (The Book of Cool, Birth of the Cool, The Birth (and Death) of the Cool) dedicated to deconstructing the word and the cultural concept behind it. Its lasting appeal is perhaps due to what the linguist Donna Jo Napoli has called its "underspecified" nature, allowing it to adapt to a myriad of contexts. No question about it, cool is in no danger of cooling off.

Update: My "On Language" column is now online here. You can also hear me talk about cool and other recent column topics on WNYC's "The Brian Lehrer Show."

Part of the interview is available on YouTube: