Fearlessness, intrepidity or daring, especially with confident disregard for personal safety, conventional thought, or other restrictions.
Insolent boldness, especially when imprudent or unconventional.
Courage, fortitude, or strength.
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.
Any fundamental support, structure, or infrastructure.