Okay I work in translation and like languages. So here goes.
Fartlek-a term used in running, Swedish I believe and if I understand it correct it is where the runner uses variable speed over one run to help in training. Still not quite understanding the concept (which isn't unusual when it comes to my training) but I love using this word as much as possible at the dinner table with my family.
Such as, "I'm going on my fartlek today." "Aidyn did you fartlek?" "Remember the good old days when we would fartlek around the city?"