firewall

/ˌfaɪərˈwɔl/

/ˈfaɪəwɔl/

Other forms: firewalls

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.

Definitions of firewall

1. noun

   a fireproof (or fire-resistant) wall designed to prevent the spread of fire through a building or a vehicle
   type of:

   wall

   an architectural partition with a height and length greater than its thickness; used to divide or enclose an area or to support another structure
2. noun

   (computing) a security system consisting of a combination of hardware and software that limits the exposure of a computer or computer network to attack from crackers; commonly used on local area networks that are connected to the internet
   type of:

   security system

   (computing) a system that enforces boundaries between computer networks
3. noun

   (colloquial) the application of maximum thrust
   “he moved the throttle to the firewall”

   type of:

   drive, driving force, thrust

   the act of applying force to propel something