central

Adjective

• in or near a center or constituting a center; the inner area
  • a central position
    

• serving as an essential component
  • a cardinal rule
    
  • the central cause of the problem
    
  • an example that was fundamental to the argument
    
  • computers are fundamental to modern industrial structure
    

Noun

• a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication

Related words

• Synonyms: 
  cardinal , fundamental , key , primal , telephone exchange , exchange