slang definition of slang
slang (countable and uncountable, plural slangs) 1  Language outside of conventional usage. 2  Language that is unique to a particular profession or subject; jargon. 3  The specialized language of a social group, sometimes used to make what is said unintelligible to those not members of the group; cant. 1871â72, George Eliot, Middlemarch, Chapter 11 Oh, there are so many superior teas and sugars now. Superior is getting to be shopkeepers' slang..