n. A secret language.
Historically, cryptolects have been especially prevalent among service nomads: outsiders who provide settled populations with services they lack but are nonetheless met with hostility and mistrust, such as Gypsy coppersmiths, Irish Travelers, or the Sheikh Mohammadi peddlers of Afghanistan.
Unlike modern slang the ancient cant approaches the notion of a…"cryptolect," as described by Ian Hancock. Altered by time, it retains a degree of currency in the British Isles and North America among Travelers, a traditionally itinerant people including the Roma (Gypsies) and other groups.
In the cryptolect of Yiddish-speaking thieves, a word for ‘prison’ is kan.