* A system intended to thwart unauthorized access to or from a private network that is often used to prevent unauthorized users from accessing private networks connected to the internet. [1]
* A set of related programs that protect the resources of a private network from users from other networks. [2]

[1] Vinson & Elkins LLP Practice Support, EDD Glossary.
[2] Kroll Ontrack, Glossary of Terms, http://www.krollontrack.com/glossaryterms

Attributions
- EDRM (http://edrm.net)