expanse in WordNet English dictionary

1. the extent of a 2-dimensional surface enclosed within a boundary
   "the area of a rectangle"; "it was about 500 square feet in area"
   area  expanse  surface area 
   
2. a wide scope
   "the sweep of the plains"
   sweep  expanse 
   
3. a wide and open space or area as of surface or land or sky
   expanse