a central or critical point in a system or network, such as for transportation, communication, or energy

central or most important part of a system or network

cardinal (Catholicism)

pivot; fulcrum

cardinal of the Catholic Church

the principle that constant activity prevents decay or stagnation, just as a frequently used door hinge does not become worm-eaten

important hub; key position

central nervous system (CNS)

literally meaning that flowing water does not rot and a door hinge does not get worm-eaten; used to signify that constant movement or exercise prevents stagnation and decay

Lingshu Jing (Divine Pivot, or Spiritual Pivot), ancient Chinese medical text (c. 1st century BC)

Dubhe; Alpha Ursae Majoris in the Big Dipper