(noun)
the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
(noun)
fortitude and determination
(noun)
a central cohesive source of support and stability
(noun)
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 shelved
(noun)
the part of a network that connects other networks together
the backbone is the part of a communication network that carries the heaviest traffic