Definitions of firewall:

  • noun:   the application of maximum thrust
    Example: "He slammed the throttle to the firewall"
  • noun:   fireproof (or fire-resistant) wall designed to prevent the spread of fire through a building or a vehicle
  • 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