Definition of: slang

(slang) noun
1. A type of popular language comprised of words and phrases of a vigorous, colorful, or facetious nature, which are invented as needed or derive from the unconventional use of the standard vocabulary. The vocabulary of slang, although usually ephemeral, may achieve wide colloquial currency, and, in the evolution of language, many words originally slang have been adopted by good writers and speakers, and ultimately taken their place as accepted English.
2. The special vocabulary of a certain class, group, or profession: college slang.
3. Originally, the argot or jargon of thieves and vagrants.
—v.t. To abuse or address with slang; also, to scold.
—v.i. To use slang. [Origin uncertain] Synonyms: argot, cant, jargon, lingo. The language of the underworld is argot, stressing its secrecy; cant often signifies the vocabulary of a special occupational group; jargon emphasizes unintelligibility and cacophonous sound. Cant, originally the beggar's whine, then the preacher's drone, acquired, in later usage, the more common meaning of sanctimonious moralizing. Jargon has as its commonest sense barbarous–sounding gabble. Lingo commonly designates foreign–sounding speech, or a language with which we are unfamiliar.