The usage of cool as a general positive epithet or interjection has been part and parcel of English slang since World War II, and has even been borrowed into other languages, such as French and German. Originally this sense is a development from a Black English usage meaning “excellent, superlative,” first recorded in written English in the early 1930s. Jazz musicians who used the term are responsible for its popularization during the 1940s. As a slang word expressing generally positive sentiment, it has stayed current (and cool) far longer than most such words. One of the main characteristics of slang is the continual renewal of its vocabulary and storehouse of expressions: in order for slang to stay slangy, it has to have a feeling of novelty. Slang expressions meaning the same thing as cool, like bully, capital, hot, groovy, hep, crazy, nervous, far-out, rad, and tubular have for the most part not had the staying power or continued universal appeal of cool. In general there is no intrinsic reason why one word stays alive and others get consigned to the scrapheap of linguistic history; slang terms are like fashion designs, constantly changing and never “in” for long. The jury is still out on how long newer expressions of approval such as def and phat will survive.