This has to be one of the silliest suggestions, not only in this incredibly silly book, but in any book, anywhere. According to Cassidy, the term ‘crusher’, a slang term for a policeman, has no connection with the English word ‘crush’. No, to go for such an obvious derivation would be the act of a racist, determined to deprive the Irish of their linguistic patrimony. In fact, says Cassidy, the word ‘crusher’ comes from the Irish phrase cuir siar ar, meaning to enforce.
Now, this phrase certainly exists in dictionaries. Of course it does. Cassidy didn’t speak any Irish so he was completely dependent on dictionaries to find words and phrases which bore some slight resemblance to his target English expressions. But the phrase isn’t a word, and it means to force something on someone. It is used like this:
Bhí sé ag iarraidh a thuairimí a chur siar orm. (He was trying to put his opinions back on me, he was trying to force his opinions on me)
Chuir siad an cógas siar air. (They put the medicine back on him, they forced him to take the medicine)
In other words, it is found in phrases like this. But why would anyone use cuir siar ar as a noun for an enforcer? Even if you don’t speak Irish, you must realise that there is something fishy about this claim. It’s like someone saying that because the phrase ‘give vent to’ exists in English, then it is quite natural to say:
*He is a give vent to. (He is someone who blows hot and cold)
*You will have to stop these give vent tos. (You will have to stop these outbursts)
Languages do differ in what they allow a speaker to do but I really don’t think any language on earth would allow you to take a phrasal verb and use it as a noun like this.
And back in the real world, crusher (as in English for person who crushes) is a pretty good description of a group of people whose task was to quell unrest and to beat miscreants off the streets. It’s certainly a better idea than cuir siar ar!
Chance of Cassidy being correct? Why even bother asking the question? The suggestion is just so utterly, completely stupid, only a total nincompoop like Cassidy could have come up with it.