Noun
1. a central cohesive source of support and stability;
"faith is his anchor""the keystone of campaign reform was the ban on soft money""he is the linchpin of this firm"2. fortitude and determination;
"he didn't have the guts to try it"3. the series of vertebrae forming the axis of the skeleton and protecting the spinal cord;
"the fall broke his back"4. the part of a network that connects other networks together;
"the backbone is the part of a communication network that carries the heaviest traffic"