Funny thing. So for years I've been meaning to look up what certain math terms mean etymologically - and recently I've been doing this on occasion. It's just for fun and I'm not being systematic about it.

Anyway, I was looking up the word "set" and it pointed to this Latin word "secta" and I thought, "Hey, that sounds like section," so I looked up section.

http://www.etymonline.com/index.php?search=Soap-rock

and while I never quite understand what these entries are telling me, section is somehow related to an OE word seax which means a short sword, but it looks like it derives from the Latin saxum which means stone.