Slang ... an attempt of common humanity to escape from bald literalism, and express itself illimitably ... the wholesome fermentation or eructation of those processes eternally active in language, by which froth and specks are thrown up, mostly to pass away, though occasionally to settle and permanently crystallise.

Walt Whitman, 1885

Most of us think that we recognise slang when we hear it or see it, but exactly how slang is defined and which terms should or should not be listed under that heading continue to be the subject of debate in the bar-room as much as in the classroom or university seminar. To arrive at a working definition of slang the first edition of the Bloomsbury Dictionary of Contemporary Slang approached the phenomenon from two slightly different angles. Firstly, slang is a style category within the language which occupies an extreme position on the spectrum of formality. Slang is at the end of the line; it lies beyond mere informality or colloquialism, where language is considered too racy, raffish, novel or unsavoury for use in conversation with strangers … So slang enforces intimacy. It often performs an important social function which is to include into or exclude from the intimate circle, using forms of language through which speakers identify with or function within social sub-groups, ranging from surfers, schoolchildren and yuppies, to criminals, drinkers and fornicators. These remain the essential features of slang at the end of the 1990s, although its extreme informality may now seem less shocking than it used to, and its users now include ravers, rappers and net-heads along with the miscreants traditionally cited. There are other characteristics which have been used to delimit slang, but these may often be the result of prejudice and misunderstanding and not percipience. Slang has been referred to again and again as ‘illegitimate’, ‘low and disreputable’ and condemned by serious writers as ‘a sign and a cause of mental atrophy’(Oliver Wendell Holmes), ‘the advertisement of mental poverty’(James C. Fernal). Its in-built unorthodoxy has led to the assumption that slang in all its incarnations (metaphors, euphemisms, taboo words, catchphrases, nicknames, abbreviations and the rest) is somehow inherently substandard and unwholesome. But linguists and lexicographers cannot (or at least, should not) stigmatise words in the way that society may stigmatise the users of those words and, looked at objectively, slang is no more reprehensible than poetry, with which it has much in common in its creative playing with the conventions and mechanisms of language, its manipulation of metonymy, synechdoche, irony, its wit and inventiveness. In understanding this, and also that slang is a natural product of those ‘processes eternally active in language’, Walt Whitman was ahead of his time.