Meaning

noun (colloquial) the application of maximum thrust

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 netwo

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

originFrom fire + wall. Compare West Frisian brânmuorre, Dutch brandmuur, German Brandmauer, Feuermauer, Swedish brandvägg, brandmur, Icelandic eldvegg. The verb sense for using maximum power or acceleration comes from the engine's firewall being the limit of forward movement of the throttle controls on many simpler vehicles; thus, to get the maximum engine output, one would push the throttle levers or…

Etymology from Wiktionary, CC BY-SA 3.0