In folklore the Piru often features as a nasty spirit of the forest with which a wise-aleck either wins or loses a battle of wits, giving or receiving a forfeit[?] in return.
The Devil is often referred to as Pääpiru, literally "Headpiru".
"Piru" is also a mild swearword in Finnish.
wikipedia.org dumped 2003-03-17 with terodump