1. the series of connected bones down the middle of the back; the spine
2. strength of character; courage and determination
3. the most important part of something; the foundation or basis

Examples

• The doctor examined her backbone for signs of injury.
• He injured his backbone in the accident and needed surgery.
• She showed real backbone when she stood up to the bullies.
• It takes backbone to start your own business.
• Small businesses are the backbone of the economy.
• Agriculture forms the backbone of the region’s economy.
• The volunteers are the backbone of our organization.