From WordNet (r) 2.0 (August 2003) [wn]:
intranet
n : a restricted computer network; a private network created
using World Wide Web software
From The Free On-line Dictionary of Computing (19 Sep 2003) [foldoc]:
intranet
<networking> Any network which provides similar services
within an organisation to those provided by the Internet
outside it but which is not necessarily connected to the
Internet. The commonest example is the use by a company of
one or more World-Wide Web servers on an internal TCP/IP
network for distribution of information within the company.
Since about 1995, intranets have become a major growth area in
corporate computing due to the availability of cheap or free
commercial browser and web server software which allows
them to provide a simple, uniform hypertext interface to
many kinds of information and application programs.
Some companies give limited access to their intranets to other
companies or the general public. This is known as an
"extranet".
(1997-07-14)