An Overpowering character is someone who can kill anything without no challenge. Are you worse at vocab than me?
Again, that's not correct.
It all depends on the scope of the game.
Let me give you an example.
There is something in the industry that can be roughly called "player balance." There's symmetrical balancing, asymmetrical balancing, and "player balancing."
Player balancing is when the player is given a temporary ability that completely overpowers the game world or has some sort of specific negative to it.
An example of this would be the Super Star in Mario and the BFG in DOOM.
The Super Star makes the player invincible (except from falling into pits), however it is a temporary invincibility. The BFG in DOOM could clear the entire screen of enemies, which is "overpowered" but it was balanced out by having a small ammo supply.
Again, it depends on the scope of the game. You can have an "overpowered" character that can tear through 90% of enemies, but if there are enemies that can stand up to the player you can still balance out a character that is "overpowered."
Scope is important. My example with the Dragon Priests is what I mean by scope.
If you stand within the aura the Dragon Priest has on them, you are no longer "overpowered" because it nulls your enchantments, stay outside the aura and you're still "overpowered" because if you happen to be playing as an Archer or Destruction Mage, you could still kill them with ease.
Scope is important.