1) Area 2) Enormousness 3) Hugeness 4) Immenseness 5) Immensity 6) Magnitude 7) Ocean 8) Sea 9) Size 10) Sizeableness 1) Bigness 2) Enormousness 3) Grandness 4) Greatness 5) Huge quality 6) Immenseness 7) Immensity 8) Largeness 9) Outer space quality 10) Property of outer space 11) Sizeableness 
• (n.) The quality or state of being vast.
Vast'ness noun The quality or state of being vast. 
vastness 1. To a great extent; immensity; such as, the vastness of the ocean or of space. 2. An immense bulk and extent; as, the vastness of a mountain. 3. An immense magnitude or amount; such as, the vastness of an army, or of the sums of money necessary to support it. 4. Of immense importance.