Gandy dancer is a term from the old days of the expansion of the railroads in America. A gandy dancer was a labourer who hooked an iron bar under the tracks, then ‘danced’ on the bar to lever the track up so that others could shovel stones and gravel underneath it.
There is no certainty about where the term came from, but there are many stories and claims. The iron pole used was called a gandy, but whether this came from the expression gandy dancer or gave rise to it is not known. Some claim that a gandy dancer was originally a fairground term for a dealer in cheap shlock. Some claim it was used by George Borrow, who died in 1881. Others say that there was a Gandy Manufacturing Company in Chicago, but there is no evidence of this. A gandy is also Newfoundland slang for a pancake and an English term for a goose.
This uncertainty was like shite to a bluebottle for Daniel Cassidy. Unfortunately, there was no appropriate term available in Irish, but he managed to find something which was close enough to fool a few suckers. His candidate was cinnte, which he claimed meant ‘constant’. In other words, the gandy dancers were ‘constantly’ dancing on the iron rod to lift the rails.
Why isn’t this a good candidate? Well, firstly, there’s the pronunciation. Imagine that somewhere there is a town in England called Kinchester. Knock off the –ster at the end, and you have a reasonable approximation for cinnte. Kin-cha, gandy. Kin-cha, gandy. Not even slightly similar, are they? And in case you don’t believe me, look at focloir.ie (http://www.focloir.ie/ga/dictionary/ei/certain), which gives sound files for the word cinnte in the three main dialects of Irish.
As for the meaning, Cassidy does his usual trick of distorting the truth and rewriting definitions. Cinnte is defined by Ó Dónaill as certain, sure; definite; mean, stingy; constant. You can find the full entry here: http://www.teanglann.ie/ga/fgb/cinnte Even though constant is given as one meaning in the dictionary, (apparently fearthainn chinnte can be used to mean constant rain, though I’ve never heard it) I don’t think any Irish speaker would give it this meaning independent of any other clues. Cinnte means sure, certain, and it’s a very common word. If someone said damhsa cinnte to me, it would make me think of it as certain dancing, or definite dancing, or determined dancing, (whatever they might mean!) not constant or continual dancing. And even if it did mean constant, isn’t this a bit strange, in English or in Irish? After all, if someone is called a dancer, isn’t this because they perform their ‘dance’ on the iron rod most of the time? So why would it be so important to specify that they do it a lot?
Of course, Cassidy again displays his ignorance of the language by mixing modern spellings from Ó Dónaill with old spellings from Dinneen, and he copies the phrase fearthainn chinnte wrongly as fearthainn cinnte, showing once again that he knew nothing about the language.
In short, wherever gandy dancer comes from, we can be quite sure it doesn’t come from the Irish adjective cinnte. This claim was first made relatively recently by a narcissistic idiot in California and it is high time it was consigned to the dustbin of crap etymologies along with the rest of Cassidy’s ridiculous theories.