Firewall
WordNet
noun
(1) (colloquial) the application of maximum thrust
"He moved the throttle to the firewall"
(2) A fireproof (or fire-resistant) wall designed to prevent the spread of fire through a building or a vehicle
(3) (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