firewall

American  

[fahyuhr-wawl] / ˈfaɪərˌwɔl /

Or fire wall

noun

1. 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.

2. 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.

3. Digital Technology. an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system.

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firewall British  

noun

1. a fireproof wall or partition used to impede the progress of a fire, as from one room or compartment to another

2. computing a computer system that isolates another computer from the internet in order to prevent unauthorized access

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firewall Scientific  

/ fîr′wôl′ /

1. A software program or hardware device that restricts communication between a private network or computer system and outside networks.

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firewall Cultural  

1. 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.

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Etymology

Origin of firewall

An Americanism dating back to 1750–60

Example Sentences

Participants need a safeguard in this regulatory vacuum, and plan sponsors need a fiduciary firewall.

From The Wall Street Journal • Mar. 27, 2026

But Rockwell’s time traveler — he really is one — is used to a firewall of resistance.

From Los Angeles Times • Feb. 12, 2026

Auto insurance is supposed to be a financial firewall when things go wrong on the road.

From MarketWatch • Dec. 23, 2025

"However, in the time since that strategy was published, events have shown that we need to consider whether our firewall is enough," he added.

From BBC • Dec. 16, 2025

It was a laptop belonging to an accountant from Edinburgh sitting in 4B who had the latest firewall installed.

From "City Spies" by James Ponti