ya, i was telling my french teacher about parkour, and she was so sure that it was misspelled. She is so sure that it is parcour. So, i guess she was half right lol.

oh well.
adding on to what m2 was saying, french words ending with a constanant letter like the word "chat" (chat is used in the french terms for pk moves) when you say chat, you don't pronounce the "t" at the end, in sounds like you're saying shay. if chat ended with an e then it would sound like shate. get it? this happends with pretty much all french words.
you might be thinking that, "parkour ends with "r" so why do we pronounce it? I guess people have modified it over the years, or it is one of those odd exceptions, although i don't know for sure what the answer would be.