backbone
//ˈbækˌboʊn//
Noun
backboneSingular
backbonesPlural
1
The series of vertebrae extending from the skull to the pelvis; the spine.
The doctor examined her backbone for any signs of injury.
2
The chief support or main factor of something; the foundation or core.
Small businesses are the backbone of the local economy.
3
Strength of character; courage, determination, or resolve.
She showed real backbone when she stood up to the bullies.