Ground round was a term used years ago referring to the leanest
ground beef. The hind leg in beef is called the round (Top round,
bottom round, eye of round and sirloin tip). Today if you were to
read a recipe asking for ground round it does not mean you actually
have a butcher ground a round roast, it just means that you need
4%-7% fat ground beef. Likewise ground sirloin would be 10%-15% fat
and ground chuck would be 20% fat.