spine

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The spinal column of a vertebrate.
2. n. Zoology Any of various pointed projections, processes, or appendages of animals.
3. n. Botany A strong, sharp-pointed, usually woody outgrowth from a stem or leaf; a thorn.
4. n. Something that resembles or suggests a backbone, as:
5. n. The hinged back of a book.
6. n. The crest of a ridge.
7. n. Strength of character; courage or willpower.

Century Dictionary and Cyclopedia

1. n. In botany, a stiff sharp-pointed process, containing more or less woody tissue, and originating in the degeneracy or modification of some organ. Usually it is a branch or the termination of a stem or branch, indurated, leafless, and attenuated to a point, as in the hawthorn, sloe, pear, and honey-locust; its nature is clearly manifest by the axillary position, and also by the fact that it sometimes produces imperfect leaves and buds. A spine may also consist of a modified leaf (all gradations being found between merely spiny-toothed leaves and leaves which are completely contracted into simple or multiple spines, as in the barberry), or of a persistent petiole, as in some Astragali and in Fouquieria, or of a modified stipule, as in the common locust. A spine is to be clearly distinguished from a prickle, which is merely a superficial outgrowth from the bark. See prickle, 1.
2. n. The backbone; the rachis, spina, or spinal column of a vertebrate. The name is due to the series of spinous processes of the several vertebræ which it presents, forming a ridge along the middle of the back. See spinal column (under spinal), and vertebra, vertebral.
3. n. A name of some part in various animals. In anatomy, a sharp process, point, or crest of bone; a spinous process, generally stouter than a styloid process: as, the spine of the ilium, of the ischium, of the scapula, of the pubis. See cuts under innominatum and shoulder-blade.
4. n. In much., any longitudinal ridge; a fin.
5. n. In lace-making, a raised projection from the cordonnet: one of the varieties of pinwork; especially, one of many small points that project outward from the edge of the lace, forming a sort of fringe.
6. n. The duramen or heartwood of trees: a ship-builders' term. See duramen.
7. n. and hemal.
8. n. One of the quills of a harpsichord or spinet.
9. n. Specifically, a sharp, columnar mass of solidified lava which was forced upward to a height of over 1,000 feet above the summit of Mount Pelée, Martinique, in 1903. See volcano, 1. It constituted a new phenomenon in vulcanology. See cut under cumulo-volcano.

Wiktionary

1. n. A person or thing's backbone; the series of bones collectively from one's (literal or figurative) head to tail or pelvis.
2. n. A rigid, pointed surface protuberance or needle-like structure on an animal, shell, or plant.
3. n. Courage or assertiveness.
4. n. The narrow, bound edge of a book.

GNU Webster's 1913

1. n. (Bot.) A sharp appendage to any of a plant; a thorn.
2. n. A rigid and sharp projection upon any part of an animal.
3. n. One of the rigid and undivided fin rays of a fish.
4. n. (Anat.) The backbone, or spinal column, of an animal; -- so called from the projecting processes upon the vertebræ.
5. n. Anything resembling the spine or backbone; a ridge.

WordNet 3.0

1. n. a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin
2. n. a small sharp-pointed tip resembling a spike on a stem or leaf
3. n. the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
4. n. the part of a book's cover that encloses the inner side of the book's pages and that faces outward when the book is shelved
5. n. any sharply pointed projection