axis - the main stem or central part about which plant organs or plant parts such as branches are arranged

notochord - a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates

chine - backbone of an animal

canalis vertebralis, spinal canal, vertebral canal - the canal in successive vertebrae through which the spinal cord passes

coccyx, tail bone - the end of the vertebral column in humans and tailless apes

vertebra - one of the bony segments of the spinal column

intervertebral disc, intervertebral disk - a fibrocartilaginous disc serving as a cushion between all of the vertebrae of the spinal column (except between the first two)

skeletal structure - any structure created by the skeleton of an organism

axial skeleton - the part of the skeleton that includes the skull and spinal column and sternum and ribs