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or fire wall

[fahyuh r-wawl] /ˈfaɪərˌwɔl/
a partition made of fireproof material to prevent the spread of a fire from one part of a building or ship to another or to isolate an engine compartment, as on a plane, automobile, etc.
a person, thing, or event that acts as a barrier or protection against something undesirable:
The new employee handbook should create a firewall against unethical business conduct.
Digital Technology. an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system.
Origin of firewall
An Americanism dating back to 1750-60 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for firewall
Contemporary Examples
Historical Examples
  • "They're probably both stuck at the firewall," Willows said.

    The Bramble Bush Gordon Randall Garrett
  • Apparently the foul-up is on the other side of the firewall.

    The Bramble Bush Gordon Randall Garrett
  • The temperature behind the firewall had risen to two-forty Centigrade.

    The Bramble Bush Gordon Randall Garrett
  • He went into the antechamber of the reactor and glared at the door in the firewall.

    The Bramble Bush Gordon Randall Garrett
  • You try to get an experimental service running and no one will reconfigure the firewall.


    Cory Doctorow
British Dictionary definitions for firewall


a fireproof wall or partition used to impede the progress of a fire, as from one room or compartment to another
(computing) a computer system that isolates another computer from the internet in order to prevent unauthorized access
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for firewall

1851 as a physical wall meant to prevent the spread of fire in a structure, from fire (n.) + wall (n.). Computer sense is by 1990.

Online Etymology Dictionary, © 2010 Douglas Harper
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firewall in Science
A software program designed to protect a network by preventing unauthorized users from gaining access or by monitoring transfers of information to and from the network.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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firewall in Culture

firewall definition

A means of separating a computer network from outside networks for security purposes. A server outside an organization's own network may be used to funnel all incoming and outgoing traffic to assist in keeping out viruses, as well as to prevent unauthorized outsiders from gaining access to a network.

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Slang definitions & phrases for firewall



  1. Computer hardware or software that protects internal networks from outside intrusion: Fire-walls, in recent years, have become the bulwark against computer break-ins (1990s+ Computer)
  2. A strong safeguard between one operation or area and another: Impenetrable firewalls between federally insured banking activities and their nonbanking commercial activities would prevent stock manipulation (1990s+)

[fr a firewall built to contain a fire in a building, a meaning found by 1851, and a barricade between an engine and a passenger compartment, found by 1947]

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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