Firewall - Definition
firewall
n 1: (colloquial) the application of maximum thrust; "he moved
the throttle to the firewall"
2: (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
3: a fireproof (or fire-resistant) wall designed to prevent the
spread of fire through a building or a vehicle