How did a metal washer get its name?

Question

This type:http://flickr.com/photos/stagewhisper/7188909/

Answer 1

http://www.etymonline.com/index.php?sear...

Answer 2

Nobody knows, and it's been studied quite a bit.  "Nut" and "bolt" are of fairly obvious ancestry, but "washer' is a stumper.  I think the first ones were used in leather armor and saddlery, so maybe that's a place to start looking.