backbones

1. a central cohesive source of support and stabilityExamples: "faith is his anchor"; "the keystone of campaign reform was the ban on soft money"; "he is the linchpin of this firm"Synonyms: anchor, backbone, keystone, linchpin, lynchpin, mainstay

2. fortitude and determinationExamples: "he didn't have the guts to try it"Synonyms: backbone, grit, gumption, guts, moxie, sand

3. the series of vertebrae forming the axis of the skeleton and protecting the spinal cordExamples: "the fall broke his back"Synonyms: back, backbone, rachis, spinal column, spine, vertebral column

4. the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelvedExamples: "the title and author were printed on the spine of the book"Synonyms: backbone, spine

5. the part of a network that connects other networks togetherExamples: "the backbone is the part of a communication network that carries the heaviest traffic"Synonyms: backbone