What makes a four-quadruple-turret battleship super

What armament would make a four-quadruple-turret British battleship a true super-battleship?

Sixteen 16-inch guns in four superfiring quadruple turrets would give the ship the scale and broadside weight implied by the label.

The proposal starts with four superfiring quadruple turrets, two forward and two aft. Replacing 14-inch weapons with 16-inch guns produces a sixteen-gun main battery. Such a broadside would move an enormous weight of shell at once. That armament, rather than the original 14-inch version, earns the super-battleship label in this answer.