The terms tanks, supports and DPS are already used in Mobas. But they're not very useful descriptions since there's so much more to the heroes/champions. Even if you say you're going to play as a tank, what kind of tank? How do you fit in the team? Are you an initiator? Can you solo a lane or take jungle camps effectively?
Also, you shouldn't mix up characters and roles. Most characters can tank, support and do damage. It's all about who can do it the best.