backbone site n.,obs.
Formerly, a key Usenet and email site, one that processes a
large amount of third-party traffic, especially if it is the home
site of any of the regional coordinators for the Usenet maps.
Notable backbone sites as of early 1993, when this sense of the
term was beginning to pass out of general use due to wide
availability of cheap Internet connections, included _uunet_
and the mail machines at Rutgers University, UC Berkeley, DEC's Western Research Laboratories, Ohio
State University, and the University of Texas. Compare rib site, leaf site.
[1996 update: This term is seldom heard any more. The UUCP
network world that gave it meaning has nearly disappeared;
everyone is on the Internet now and network traffic is
distributed in very different patterns. Today one might see
references to a `backbone router' instead --ESR]