horizon

Noun

• the great circle on the celestial sphere whose plane passes through the sensible horizon and the center of the Earth

• a specific layer or stratum of soil or subsoil in a vertical cross section of land

• the range of interest or activity that can be anticipated
  • It is beyond the horizon of present knowledge
    

• the line at which the sky and Earth appear to meet

Related words

• Synonyms: 
  celestial horizon , view , purview , apparent horizon , visible horizon , sensible horizon , skyline