The term RELATING TO THE BACKBONE can be summarized by the word SPINAL, which is a six-letter word. SPINAL refers to the vertebral column, which is commonly known as the backbone. It is a long, curved structure that runs from the base of the skull to the lower back and is made up of 33 individual bones. The SPINAL cord runs through the vertebral column and is responsible for carrying nerve signals between the brain and the rest of the body.