sphere in WordNet English dictionary

1. a particular environment or walk of life
   "his social sphere is limited"; "it was a closed area of employment"; "he's out of my orbit"
   sphere  domain  area  orbit  field  arena 
   
2. the apparent surface of the imaginary sphere on which celestial bodies appear to be projected
   celestial sphere  sphere  empyrean  firmament  heavens  vault of heaven  welkin 
   
3. a particular aspect of life or activity
   "he was helpless in an important sector of his life"
   sector  sphere 
   
4. any spherically shaped artifact
   sphere 
   
5. the geographical area in which one nation is very influential
   sphere  sphere of influence 
   
6. a solid figure bounded by a spherical surface (including the space it encloses)
   sphere 
   
7. a three-dimensional closed surface such that every point on the surface is equidistant from the center
   sphere