firewall

American  

[fahyuhr-wawl] / ˈfaɪərˌwɔl /

Or fire wall

noun

firewalls plural

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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Other Word Forms

Noun Inflected Forms

• firewalls
  plural

Etymology

Origin of firewall

An Americanism dating back to 1750–60

Explanation

A sturdy barrier that's flame resistant is called a firewall. Another kind of firewall is the one a computer system uses to block potentially dangerous external networks or hackers. The original firewall was exactly what it sounds like: a wall that provides a safe barrier against fire. These firewalls are often used in large buildings (or between structures that are connected) to prevent a fire from spreading once it's started. The term was borrowed to describe something in computing that plays a similar role, limiting the access to a network, usually from the internet. Your firewall helps protect your computer against viruses and malware.

Example Sentences

See Examples For:

firewall firewalls

Such a deal would aim to create a firewall between Tesla’s Chinese subsidiary and its U.S. business.

From The Wall Street Journal ● Jul. 31, 2026

Following the latest revelations, historian David Olusoga told BBC Newsnight there is now "a desperate desire within government and within the palace to draw a firewall… between this crisis and the wider monarchy".

From BBC ● Feb. 21, 2026

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

From Los Angeles Times ● Feb. 12, 2026

The built-in R.O.B.E.R.T. firewall blocks ads, trackers, and malware before they reach you.

From Salon ● Feb. 12, 2026

This system is of course protected, but the firewall isn't very secure.

From "Counting by 7s" by Holly Goldberg Sloan

The software bug was capable of crashing an operating system used by firewalls, servers and network appliances.

From The Wall Street Journal ● Apr. 14, 2026

The existing players in cybersecurity provide businesses with complex firewalls: software that identifies customers’ internal users of data, and tools that allow or disallow access to information for parties external to the customer.

From Barron's ● Feb. 17, 2026

They contain servers, storage systems and network equipment like routers and firewalls, along with the necessary power and cooling systems to operate them.

From BBC ● Oct. 14, 2025

Yu notes that lack of firewalls for sensitive personal information within the federal government and how they plan to use this data are all causes for concern.

From Salon ● Feb. 21, 2025

Then, last night, just before I’d succumbed to exhaustion, I’d finally managed to navigate my way through the intranet’s labyrinth of firewalls and into the main Oology Division database.

From "Ready Player One: A Novel" by Ernest Cline