[spine] n [ME, thorn, spinal column, fr. L spina; perh. akin to L spica ear of grain] (15c) 1 a: spinal column b: something resembling a spinal column or constituting a central axis or chief support c: the part of a book to which the pages are attached and on the cover of which usu. appear the title and author's and publisher's names
2: a stiff pointed plant process; esp: one that is a modified leaf or leaf part
3: a sharp rigid process on an animal: as a: spicule b: a stiff unsegmented fin ray of a fish c: a pointed prominence on a bone -- spined adj -- spine.like adj