From Freepedia
- The backbone is a synonym for the spine of a vertebrate organism.
- The high-traffic-density connectivity portion of any communications network.
- In packet-switched networks, a primary forward-direction path traced sequentially through two or more major relay or switching stations.: primarily switches and interswitch trunks. (Source: from Federal Standard 1037C and from MIL-STD-188)
- The Internet backbone.
- In transportation backbone has a similar meaning. More generally it is the most important part.
- Backbone chain in polymer chemistry refers to the framework of the molecule.