In American English, the word sore is used to mean angry or upset. This is a natural extension of the original meaning of sore, which is ‘in pain’ or hurt. After all, another way of saying that someone was sore is that they were hurt. Daniel Cassidy, in his moronic book How The Irish Invented Slang, ignores this obvious and reasonable explanation and claims that sore comes from the Irish word sár, which he claims means ‘outrage, bitterness, humiliation’.
It doesn’t. In Ó Dónaill’s dictionary, it is described as Lit., which means that it is an obsolete, literary term. And Ó Dónaill defines it as ‘violation, outrage, humiliation’. Cassidy has completely changed the meaning here with a subtle change of language. You can feel outrage, or you can carry out an outrage. You can feel humiliation or you can inflict a humiliation on someone else. A violation is fairly unambiguous, so Cassidy dropped it and replaced it with the inappropriate word ‘bitterness’. In other words, sár is something bad done to you by someone else or their negative attitude to you, so it doesn’t correspond to sore in English. You don’t say ‘I was an outrage’ when someone makes you cross!
It would be very easy to make Cassidy-type claims for other languages based solely on the sound of words with a slightly similar meaning. What about sore coming from German sauer, meaning sour? ‘He was sour at me’ would certainly fit the bill! Or how about using some of Cassidy’s creative adaptation of sources to turn the French sourd, meaning deaf, into ‘deaf, feigning deafness, fig. angrily silent’?
Once again, Cassidy’s version is clearly and demonstrably nonsense.