backbone

/ˈbækˌboʊn/

IPA: /B AE1 K B OW0 N/

noun
  1. 1

    The series of vertebrae, separated by disks, that encloses and protects the spinal cord, and runs down the middle of the back in vertebrate animals.

  2. 2

    Any fundamental support, structure, or infrastructure.

    Before automobiles, railroads were a backbone of commerce.

  3. 3

    Courage, fortitude, or strength.

    He would make a good manager, if he had a little more backbone.

Source: https://en.wiktionary.org/wiki/backbone