What does Battle of Ontario mean?

Battle of Ontario meaning in Urban Dictionary

if the NHL's Toronto Maple Leafs and their particular arch-rivals, the Ottawa Senators, play both. Extreme during regular season but much more therefore through the playoffs. Every Battle of Ontario into the post-season is obtained because of the Maple Leafs(4-2 in 2000, 4-0 in 2001, 4-3 in 2002, 4-3 in 2004).