the.com/argot

means The specialized slang of a particular group or trade, built to signal insider status and keep outsiders guessing.

from Argot entered English from French, where it originally referred specifically to the secret jargon of thieves and beggars in medieval and early modern France. Its ultimate root is uncertain — one old guess ties it to 'Ragot,' a supposed figure associated with the beggars' guild, but this is folk etymology, not established fact. What's solid is the French thread: by the time English borrowed the word, it had already widened from criminal cant to mean any group's private vocabulary.