/ spaɪn; NAmE / noun
1.
the row of small bones that are connected together down the middle of the back
SYN backbone —picture at skeleton
2.
any of the sharp pointed parts like needles on some plants and animals :
Porcupines use their spines to protect themselves.
—see also spiny
3.
the narrow part of the cover of a book that the pages are joined to
••
WORD ORIGIN
late Middle English : shortening of Old French espine , or from Latin spina thorn, prickle, backbone.