backbone - noun

a central cohesive source of support and stability

fortitude and determination

the series of vertebrae forming the axis of the skeleton and protecting the spinal cord

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 part of a network that connects other networks together

backbone - thesaurus

anchor   back   grit   gumption   guts   keystone   linchpin   lynchpin   mainstay   moxie   rachis   sand   spine