There was ridicule regarding that word in the anthem. There still is.
It means in context of the island of Australia “Surrounded by water.”
Etymology - Middle English ( spoken and written in England from about 1100 to about 1500) Girden meaning encircle.
I’m glad it wasn’t just me Rose!
I still remember the words to those traditional hymns, not that I’d volunteer to get up on the stage and sing Holy Holy Holy these days!
I know, suppose what I was saying is a list of songs could be picked up from a radio, not exclusively School, it would be hard to know exactly where you first heard a song.