spine

Your spine is your backbone. When you sit and stand with your spine straight, people will compliment you on your good posture.

Besides being the basic part of a vertebrate's skeleton, a spine is also a sharp spike, like the spines on a sea urchin or a cactus. Another kind of spine is the "backbone" of a book, the part of its cover that you can read when the book is on a bookshelf. Spine comes from the Latin spina, which also means both "backbone" and "thorn."

Definitions of spine
  1. noun
    the series of vertebrae forming the axis of the skeleton and protecting the spinal cord
    synonyms: back, backbone, rachis, spinal column, vertebral column
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    types:
    notochord
    a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates
    chine
    backbone of an animal
    urochord
    a notochord of a larval tunicate typically confined to the caudal region
    type of:
    skeletal structure
    any structure created by the skeleton of an organism
  2. noun
    any sharply pointed projection
    synonyms: acantha, spur
    see moresee less
    type of:
    projection
    any solid convex shape that juts out from something
  3. 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
    see moresee less
    types:
    ray
    any of the stiff bony spines in the fin of a fish
    quill
    a stiff hollow protective spine on a porcupine or hedgehog
    type of:
    appendage, outgrowth, process
    a natural prolongation or projection from a part of an organism either animal or plant
  4. noun
    a small sharp-pointed tip resembling a spike on a stem or leaf
    synonyms: pricker, prickle, spikelet, sticker, thorn
    see moresee less
    types:
    glochid, glochidium
    a barbed spine or bristle (often tufted on cacti)
    type of:
    aculeus
    a stiff sharp-pointed plant process
  5. noun
    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 title and author were printed on the spine of the book”
    synonyms: backbone
    see moresee less
    type of:
    part, portion
    something less than the whole of a human artifact
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