definition of
[backbone]

[1] #1 backbone n. [anchor, mainstay, keystone, linchpin, lynchpin] 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". wn

[2] #2 backbone n. [grit, guts, moxie, sand, gumption] fortitude and determination; "he didn't have the guts to try it". wn

[3] #3 backbone n. [spinal column, vertebral column, spine, back, rachis] the series of vertebrae forming the axis of the skeleton and protecting the spinal cord; "the fall broke his back". wn

[4] #4 backbone n. [spine] 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; "the title and author were printed on the spine of the book". wn

[5] #5 backbone n. the part of a network that connects other networks together; "the backbone is the part of a communication network that carries the heaviest traffic". wn