Definitions
1.nounThe series of bones situated at the back from the head to the pelvis of a person, or from the head to the tail of an animal; backbone, vertebral column.
2.nounSomething resembling a backbone, such as a ridge, or a long, central structure from which other structures radiate.
3.nounA pointed, fairly rigid protuberance or needle-like structure on an animal, shell, or plant.
4.nounThe heartwood of trees.
5.nounCourage or assertiveness.
6.nounThe stiffness of an arrow.