The Oxford Thesaurus An A-Z Dictionary of Synonyms - backbonen.

1) spine, spinal column: He's much better since the surgery on his backbone. 2) mainstay, chief or main support, buttress, pillar: Sheila has been the backbone of the society, but she has now moved away. 3) resoluteness, sturdiness, firmness, determination, strength (of character) , mettle, purposefulness, resolution, courage, fortitude, resolve, will, will-power, strength, stability, stamina, staying power, grit: Has she the backbone to run the company alone?