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.
In his work of etymological fiction, How The Irish Invented Slang, the late Daniel Cassidy claimed that the word tantrum in English derives from the Irish word teintrighim (tintrím as it would be in modern spelling), which would be pronounced chen-chreem. This is a real word from Dinneen’s dictionary. Dinneen defines it as ‘I flash forth, lighten, brighten, glisten’.
I need hardly point out that while this word exists (it’s in a dictionary) it is hard to think of any circumstance where it would actually be used, as storms rarely speak, even in stories. As usual, Cassidy does not simply copy the meanings given by Irish scholars, so his definition of the word is: ‘I flash-forth; fig. I have a tantrum or fiery fit’.
Back in reality, the origin of tantrum is almost certainly traceable to the name of a devil in English folklore, Tantrum-Bobus. This was used as a nickname for a boisterous child and eventually, it came to have the meaning of a fit of anger. For example, in the 1810s, in his diary, Henry Monro gives a list of his brother Tom’s rows with family members, including “a tantrum bobus with my mother”. Monro was a Londoner.