spine vs tail bone

spine and tail bone both are nouns.

Word	Noun	Adjective	Verb	Adverb
spine	Yes	No	No	No
tail bone	Yes	No	No	No

spine (noun)	tail bone (noun)
a sharp rigid animal process or appendage; as a porcupine quill or a ridge on a bone or a ray of a fish fin	the end of the vertebral column in humans and tailless apes
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
the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
a small sharp-pointed tip resembling a spike on a stem or leaf
any sharply pointed projection