spine
spine \'spi-n\ n [ME, thorn, spinal column, fr. L spina; akin to Latvian spina twig] 1a: SPINAL COLUMN 1b: something resembling a spinal column or constituting a central axis or chief support 1c: the backbone of a book 2: a stiff point plant process; esp : one that is a modified leaf o r leaf part 3: a sharp rigid process on an animal : as 3a: SPICULE 3b: a stiff unsegmented fin ray of a fish 3c: a pointed prominence on a bone