I teach a few classes on the Irish singing tradition to a mixed bag of mainly European students, most of whom have excellent English. Only once have I been asked about the meaning of a word. "It seems to be in lots of songs - but I've never heard it in conversation" said the student. What was the word? "Alas"!
That said, there are lots of upbeat Irish songs as well - but they dont't tend to communicate at the same emotional intensity as the sadder ones.