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.
Apparently the phrase ‘ground sweat’ is an old slang expression for a grave, and the phrase ‘to flog ground sweat’ means to speak ill of the dead.
There is no mystery about the origin of these expressions. A ground sweat is a reference to the liquefaction of the body when it’s buried, as in the proverb ‘a ground sweat cures all diseases’. (In other words, death puts an end to all sickness.)
Daniel Cassidy, in his book of false etymologies, How The Irish Invented Slang, claimed that this comes from an ‘Irish’ phrase fliuchadh grian-suite, which he claims means ‘wetting a sunny place,’ or pissing on someone’s grave. Cassidy claims that suite is the Irish for a site (it isn’t, though it is the genitive of suí meaning site.) This would be appropriate in the grammar of fliuchadh griansuite (wetting of a sunny place), if such a term existed, but would make no sense without the fliuchadh. There, it would have to be griansuí, which does not resemble ground sweat.
However, while many American cemeteries have names like Sunnylands, there is no evidence that griansuí (sunsite) has ever been used in the Irish language to mean a grave, though Cassidy states this imaginary definition as established fact. This is yet another example of Cassidy’s apparent inability to distinguish between the truth and his own inventions.
In short, this phrase is completely comprehensible in terms of English. Cassidy’s Irish candidate is pure fabrication and completely lacking in evidence.