- a partition made of fireproof material to prevent the spread of a fire from one part of a building or ship to another or to isolate an engine compartment, as on a plane, automobile, etc.
- a person, thing, or event that acts as a barrier or protection against something undesirable: The new employee handbook should create a firewall against unethical business conduct.
- an integrated collection of security measures designed to prevent unauthorized electronic access to a networked computer system.
- a fireproof wall or partition used to impede the progress of a fire, as from one room or compartment to another
- a computer system that isolates another computer from the internet in order to prevent unauthorized access
