名詞 back bone:

1. a central cohesive source of support and stability
   同義詞：anchor, mainstay, keystone, backbone, linchpin, lynchpin
2. fortitude and determination
   同義詞：backbone, grit, guts, moxie, sand, gumption
3. the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
   同義詞：spinal column, vertebral column, spine, backbone, back, rachis
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 shelved
   同義詞：spine, backbone
5. the part of a network that connects other networks together
   同義詞：backbone