central

(noun) a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication. Synonyms: telephone exchange, exchange.

(adj) serving as an essential component. Synonyms: cardinal, fundamental, key, primal. Examples: "A cardinal rule." "The central cause of the problem." "An example that was fundamental to the argument." "Computers are fundamental to modern industrial structure."

(adj) in or near a center or constituting a center; the inner area. Synonyms: central (vs. peripheral). Example: "A central position."