Another ludicrous claim of Cassidy’s is that the word bailiwick (meaning someone’s sphere of influence or control) is from the Irish baile aíoch. This is clearly rubbish for two reasons.
Firstly, the phrase baile aíoch is completely unattested in Irish outside of Cassidy’s fantasy version of the language, although the two elements which Cassidy put together to make this phrase, baile and aíoch, do exist. Baile means home or town, while aíoch means hospitable, and is related to the word aoi, meaning guest. So this phrase might just mean “hospitable home”, though the word aíoch is not very common.
So what’s wrong with this as the origin of bailiwick? Let’s imagine a group of Irish-speaking gangsters discussing their activities in New York in the 19th century. Are they really going to refer to their ceantar (area) or ríocht (kingdom) or fearann (domain) or talamh (ground, land) as mo bhaile aíoch? I can’t see it. It is an unlikely enough phrase anyway, but if I did hear it, I would think of a guest house, or their own house, or even the old home back in the Old Country, not an area which is under someone’s control in a city.
It is also highly unlikely that the word aíoch (pronounced ee-okh or ee-oh] would become wick in English.
And in any case, if Cassidy had done some basic research (something he was obviously too lazy or stupid to do) he would have realised that bailiwick has been in English for nearly six hundred years. It means the area of influence of a bailiff. The most famous bailiwick is probably the Bailiwick of Jersey in the Channel Islands, which obviously has no connection with the hospitable homes of Irish wise-guys.