The meaning of the word 'irony' has changed in what people mean when they use it. It suffered from being an obscure word which gained popularity without most people ever being taught what it means and only learning from context. All words are made up, there's no 'real' meaning.

Another word like this is 'crisis'. It went from meaning "decision" in old Greek to something like "tipping point, or a time of major change" to how most people use it today "time when lots of bad stuff happens". Much of English is poorly translated and pronounced French. Déranger in French is to bother, to be deranged in English... French itself being malformed Roman... you get the picture.

If you go chasing what words "really" mean, you'll learn that almost all of English is loan words which mean something not entirely unlike the word borrowed, and you'll end up trying to reconstruct 7000 year old languages to get to the bottom of a bottomless well.