A private or internal network that uses standard internet protocols so it has the appearance of a Web site. 1
A network of interconnecting smaller private networks that are isolated from the public Internet. 2
A computer network usually that usually restricts access only to those within the firm or corporation. The term is often used to discuss documents stored as web pages, but it can be extended to any kind of computer resource. An internal (to the company) version of the internet.
Legal Electronic Document Institute, Basic Principles of Automated Litigation Support (2005).