freespace
/ˈfriːˌspейʃ/Definitions
1. noun
a three-dimensional space or volume that is not occupied by a physical object or structure
“The designers had to work with the limited freespace to create a functional and aesthetically pleasing interior.”
2. noun
in computer graphics, a three-dimensional area or volume that is not occluded by other objects
“The game engine used freespace calculations to determine the visibility of objects on the screen.”