expanse/ˈɪks.pæns/Pluralexpanses1the extent of a 2-dimensional surface enclosed within a boundarySynonyms: areasurface area2a vast, open area or surfaceThe wide expanse of the ocean seemed to go on forever.The night sky was a breathtaking expanse of stars and constellations.The desert stretched out as an endless expanse before us.Synonyms: vastsweep3a wide and open space or area as of surface or land or sky