Canadian Football League
The CFL or Canadian Football League is the only professional football league currently active in Canada. The CFL differs from the National Football League by having a larger playing field, having 12 players per side, and having a total of only 3 downs to move the ball 10 yards. Additional differences include in the CFL if a receiving team does not play the ball, the kicker and his teammates can attempt to catch and advance the ball. The Official CFL Rule book is located on their website .
The teams of the CFL compete for the Grey Cup, named for the Canadian Governor General Earl Grey. The Winners of the Grey Cup since 1909 are posted on the CFL's website here: 
It also can stand for compact fluorescent lightbulb, a new technology meant to replace incandescent lightbulbs, discovered by Thomas Edison. CFL's use less energy than incandenscent lightbulbs, as the power usage is much less to provide the same amount of light. CFLs contain mercury, which complicates their disposal.