Why is the ninth month called September?
1610s, from Latin vertebra "joint or articulation of the body, joint of the spine" (plural vertebræ), perhaps from vertere "to turn" (see versus) + instrumental suffix -bra. The notion is of the spine as the "hinge" of the body.
vertebra ver·te·bra (vûr'tə-brə)
n. pl. ver·te·bras or ver·te·brae (-brā', -brē')
Any of the bones or cartilaginous segments of the spinal column, usually 33 in number.
Plural vertebrae (vûr'tə-brā', -brē') or vertebras
Any of the bones that make up the vertebral column. Each vertebra contains an arched, hollow section through which the spinal cord passes. In humans, the vertebrae are divided into cervical, thoracic, and lumbar sections, and the sacrum and coccyx are both made up of a series of fused vertebrae. The vertebrae are separated by cartilaginous intervertebral disks. See more at skeleton.