Backbone

1. n. Firmness; moral principle; steadfastness.
2. n. The column of bones in the back which sustains and gives firmness to the frame; the spine; the vertebral or spinal column.
3. n. Anything like , or serving the purpose of, a backbone.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.