Is there a difference between spine and backbone in use or in meaning? I think they both mean the same and can be replaced by each other. However, I'd say backbone is used more in figurative speech, but this is just a guess on my part.

3 Answers 3


Backbone and spine are both common names for the vertebral column, the series of bones from one's head to pelvis. In my personal opinion, backbone comes across as more of an informal name than spine.

It is worth noting that both of these words, however, have other meanings as well:

  • Spine can also be used to refer to a needle-like protrusion on plants and animals (among other things) such as a thorn. It can also reference the bound edge of a book.
  • Backbone can also be used to refer to nearly any fundamental support structure. For example, an internet backbone, which is the top level of inter-connectivity between core pieces of the internet.
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    Yes, like many of our words, the Latinate one (spine) is the more elite form, while the Germanic one (backbone) is more informal.
    – Kosmonaut
    Jun 25, 2011 at 14:59

The term "backbone" is pretty much restricted to a single idiom: to "show some backbone," which means to be brave or resolute.

In this phrase, you can substitute the word "spine," and the meaning is unchanged. In almost any other conceivable instance, you'll want the word "spine," as in, "she injured her spine in the accident."

Edit: The above only refers to mammalian physiology. Figurative or metaphorical uses of "backbone," such as "ATT is the backbone of the Internet" or such is a different matter.

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    Also worth noting that, adjectivally, the subject of your idiom would be considered spineless. Jun 25, 2011 at 13:03
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    I'd say I hear backbone used about as much as spine far beyond the context of this idiom.
    – Karl
    Jun 25, 2011 at 13:04
  • @Karl: ngrams.googlelabs.com/…
    – The Raven
    Jun 25, 2011 at 13:09
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    It's funny that in denoting bravery or courage, 'spine' and 'backbone' are interchangeable ... However, to indicate the opposite, you would say that somebody was either 'spineless', or 'lacking in backbone'. (I certainly have never heard anyone accuse another of being 'backboneless'.) Jun 26, 2011 at 3:15
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    @brachomonacho I would have said that spineless was far more common usage than lacking in backbone; the latter might be as infrequent as backboneless. Mar 5, 2012 at 14:09

As reported by the NOAD, the meaning of backbone is:

  • the series of vertebrae extending from the skull to the pelvis
  • (figurative) the chief support of a system or organization; the mainstay
  • (figurative) strength of character; firmness
  • the spine of a book

For those meanings, there is a similar meaning for spine.

In zoology and botany, spine is also any hard pointed defensive projection or structure, while in geology it means also "a tall mass of viscous lava extruded from a volcano."
In biochemistry, backbone means also "the main chain of a polymeric molecule."

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