What does the word backbone mean?

Usage examples for backbone

  1. Or weakness of the backbone. – Dixie Hart by Will N. Harben
  2. You'd be surprised to know how easy it is to break a lion's backbone, especially if it's a young lion. – Careers of Danger and Daring by Cleveland Moffett
  3. If they have not the backbone to produce what they feel they ought to produce, without regard to what the public wants, then good- bye to progress of any kind. – Another Sheaf by John Galsworthy