From Latin corpus (body). Ultimately from the Indo-European root kwrep- (body, form) that is also the source of corps, corpse, corporation, corset, corsage, and leprechaun.

I love that there is almost always one word in the list that makes me do a double take, like the Sesame Street song "one of these things is not like the others." What on earth is that leprechaun doing in there?

I am surprised to find 'leprechaun' here, though. I had always been told that it is the Gaelic term 'leath-brógán' (half-shod) and that it refers to the way the wee man usually gets caught: you come upon him unawares as he mends his shoe. You catch him before he slips away, and then you can force him to reveal the whereabouts of his crock of gold.

I have found that gold myself.

OK, let me go, I'll tell you where to look. All is revealed here: http://www.bbc.co.uk/dna/h2g2/brunel/A954759

The one-shoe explanation might could be a folk etymology. AHD has leprechaun from an Old Irish word meaning 'small body'.

'small body'

I like the range of meanings for the reflexes of PIE *leghw- 'light' (link): Latin levis, English leaven, carnival, light, lungs, and Irish lú 'small'.

Thank you for the scientific info on the rainbow of which I've understood half, but which I have once in a lifetime seen whole from one fading point to the other. (rainbows seem to evaporate at their endings so the little corpus delictum sits not in colors but in greys).
Also this phenomenan of the double rainbow is a visual reality in this, that there often is a parallel, more faint rainbow accompanying the clear one. I've seen both Ireland and Holland often have beautiful rainbows.

In the second rainbow the colors are in reverse order. I've seen a triple rainbow in Flagstaff, AZ.

Apparently there's another circle of rainbow behind you, but you can't see it. They work it out from refraction angles.

The "little body" explanation is reasonable; a lot of letter-orders get reversed in Irish (bosca is box, srón is nose, the name Ó Hirile is translated to Hillery) so brog could be from the same root as corp-.

However, the -án suffix, if it doesn't denote 'a person with this property' (amadán = fool), usually means something big. Its opposite is -ín meaning small (as in smithereens). Just like Italian: violone = a big viola, violino = a little one.

Ah I get it. The -án denotes the person, the le- denotes the half size. What an amadán, not to see that earlier.

Nice, though I'll never understand the finesses of rainbows.
Leprechauns and rings of stones. Never set foot in this ring of stones. I'll always remember the car crash we had after I did so.

I got to within ten feet of the end of the rainbow driving to a Tacoma Rainiers game one time. It was right behind the car in the lane just to the left of me. He was a little ahead of me and the rainbow end was chasing after him. Maybe he was a leprechaun with a pot of gold in his trunk. Then there was the rainbow that ended in the dump outside of Flagstaff that one day. Never found the pot with or without a leprechaun.

Was he driving a green compact with European plates?

That I don't remember, but there are leprechauns native to the US. I know this from the old comic strip Barnaby. They speak with a New Jersey accent.

M..................................................... 0........0 ? (oh, I know it's very very lame, but'... I'm so glad my net connection is working for a change)