Slang, jargon; as used by Patron-Minette, the Thénardiers, and other denizens of the underworld. A Mini-Dictionary of Argot
A unique language used in subcultures such as prison culture.
Argot (French for "slang") is primarily slang used by various groups, including but not limited to thieves and other criminals, to prevent outsiders from understanding their conversations. For example: "He philosophized and recited baseball statistics in a Brooklyn argot that was fast-fading." Bruce Sterling defines argot as "the deliberately hermetic language of a small knowledge clique.... a super-specialized geek cult language that has no traction in the real world."