Hah TIL. So it's the river Welsh river on the English side of the Bristol channel.

I often feel like I would understand a lot more names if I bothered learning Welsh. It's pretty popular for made up climbing route names too, because Wales is so good for it I guess. Allegedly some of the classics in the Avon gorge are Welsh derived but I could never figure them out to be sure.

You avon a chwerthin?

The Welsh "afon" derives from the earlier Celtic "abona" meaning "river". Also related to the Celtic "afanc" which was some kind of aquatic monster.