Wales is to Welsh as Sumer is to Sumerian
Cymry is the name of Wales in Welsh and Ki.EN.GI is the name of Sumer in Sumerian.
Cymraeg is to Welsh as Ki.EN.GI(R) is to Sumarian.
The Akkadians gave Ki.EN.GI the name Shumeru from which we get Sumer, but no one knows why since it is not a word in their language either.
Like the name KMT for Egypt, there are many imaginative definitions. The only obvious thing is that all these languages arose from a common source.
As verb, KA means to wish or desire. As a noun, it means spirit. Then, came the Tower of Babel and KA means whatever you wish (or KA) it to. Some say horse or land, while others say what? Hehe!
If you do no think that is funny, then consider the irony of Obama shutting down the SPAWAR Cold Fusion research which costs pennies while spending close to a trillion dollars by now on a Hot Fusion Reactors which never produce any excess energy.