n 1: the series of vertebrae forming the axis of the skeleton and
protecting the spinal cord; "the fall broke his back"
[syn: spinal column, vertebral column, backbone, back, rachis]
2: any pointed projection [syn: spur]
3: a sharp-pointed tip on a stem or leaf [syn: thorn, prickle, pricker, sticker]
4: a sharp rigid animal process or appendage; as a porcupine
quill or a ridge on a bone or a ray of a fish fin