For some time now, some of my on-line friends have advised me to provide a version of CassidySlangScam without the invective aimed at Cassidy and his supporters. In response to that advice, I am working on providing a glossary of the terms in Cassidy’s ludicrous book How The Irish Invented Slang with a short, simple and business-like explanation of why Cassidy’s version is wrong.
Cady seems to be an old term for a highwayman. It does not come from the Irish gadaí, as Cassidy claims, which is the general Irish word for a thief and sounds nothing like cady (it is pronounced gaddy). We do not know where cady comes from but it is likely to be from the name of a famous highwayman called William Cady, a brutal thug, murderer and rapist from Norfolk who became well-known in the reign of James II.