Where it’s found: Henry IV Part I, Act I, Scene III

How it’s used:

HOTSPUR: Three times they breathed and three times did
they drink,
Upon agreement, of swift Severn’s flood;
Who, then, affrighted with their bloody looks,
Ran fearfully among the trembling reeds,
And his his crisp head in the hollow bank,
Bloodstained with these valiant combatants.

Where it comes from: One of the great things about Shakespeare was how he could combine two old words to make one brand spanking new one. He did it with puppy-dog, with arch-villain, with eyeball — and now with bloodstained. (I feel like putting all of those into one sentence makes for a macabre story…)

So, where does blood come from? The bloodthirsty Anglo-Saxons gave us the word through their term blod. It has a long and storied history in other Germanic languages, popping up in Frisian, Old Norse, Middle Dutch, and Gothic, among others. In fact, its root is also responsible for the word flower in the Gothic tongue, leading etymologists to speculate that the proto-Germanic word meant “that which bursts forth.” [source]

Stained, as a noun, was much newer in Shakespeare’s day than blood. The verb was in use before that, and it appears to be a linguistic mutt. Old Norse had a word steina, meaning “to paint,” and Middle English had a word disteynen, meaning “to discolor.” The latter, in turn, came from a combination of Old French and Latin, emerging out of the word that meant “to dye,” which is also the root of the word tincture. [source]

As Ron Weasley might say, “Bloody brilliant.”