[1] : The Collaborative International Dictionary of English v.0.48

backbone \back"bone"\ ba^k"b=on`, n. 2d back, n. + bone.
   1913 webster
   1. the column of bones in the back which sustains and gives
      firmness to the frame; the spine; the vertebral or spinal
      column.
      1913 webster

   2. anything like, or serving the purpose of, a backbone.
      1913 webster

            the lofty mountains on the north side compose the
            granitic axis, or backbone of the country. --darwin.
      1913 webster

            we have now come to the backbone of our subject.
                                                  --earle.
      1913 webster

   3. firmness; moral principle; steadfastness.
      1913 webster

            shelley's thought never had any backbone. --shairp.
      1913 webster

   to the backbone, through and through; thoroughly; entirely.
      "staunch to the backbone." --lord lytton.
      1913 webster
see also:
to the backbone 

Backbone >> B Words
Backbone, definition of term: Backbone
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