spine 
/ˈspaɪn/ noun
plural spines /ˈspaɪn/ noun 1 [count] : the row of connected bones down the middle of the back : backbone
▪ This X-ray shows her spine. — see picture at human 2 [count] : a sharp, pointed part on an animal or plant
▪ Hedgehogs are covered with spines. ▪ cactus spines 3 [noncount] informal : courage or strength of character
▪ They lack the spine to do what needs to be done. 4 [count] : the part of a book to which the pages are attached
▪ Stack the books so that all the spines are facing the same way. ◊A book's spine often has the title and author's name printed on it.
▪ This X-ray shows her spine. — see picture at human
▪ Hedgehogs are covered with spines. ▪ cactus spines
▪ They lack the spine to do what needs to be done.
▪ Stack the books so that all the spines are facing the same way. ◊A book's spine often has the title and author's name printed on it.
up/down your spine
◊If something sends a chill/shiver up/down your spine or if a chill/shiver runs up/down your spine, you become frightened, thrilled, etc.
▪ Her performance of the national anthem sent a chill up my spine. [=her performance was thrilling and emotional] ▪ The very thought of what those people did sends a shiver down my spine. [=scares me] ▪ A (cold) shiver ran down my spine when I heard his voice.
▪ Her performance of the national anthem sent a chill up my spine. [=her performance was thrilling and emotional] ▪ The very thought of what those people did sends a shiver down my spine. [=scares me] ▪ A (cold) shiver ran down my spine when I heard his voice.
