Meaning

noun informal language consisting of words and expressions that are not considered appropriate for formal occasions; often vituperative or vulgar

noun a characteristic language of a particular group (as among thieves)

verb use slang or vulgar language

originFirst use appears c. 1756, meaning "special vocabulary of tramps or thieves", origin unknown. Not believed to be connected with language or lingo. Possibly derived from a North Germanic source, then possibly related to Nordic language: Danish slænge, Icelandic and Norwegian Nynorsk slengja, Norwegian slenge, Swedish slänga (“to (carelessly) sling, throw, hurl; throw away, to dispose of; to…

Etymology from Wiktionary, CC BY-SA 3.0