firewall
UK: ˈfaɪə.wɔːl | US: ˈfaɪr.wɑːl
n. 1. A physical or digital barrier designed to prevent unauthorized access (e.g., network security).
n. 2. A fireproof wall to stop the spread of flames in buildings.
vt. To protect (a system or space) with a firewall.
The term combines "fire" (Old English fȳr, from Proto-Germanic fōr) and "wall" (Old English weall, from Latin vallum). Originally literal (a wall to block fire), it was adopted in computing (1980s) as a metaphor for digital barriers that "block" threats like firewalls block flames. The logic reflects functional similarity—both protect by containment.
The IT team installed a robust firewall to safeguard sensitive data.
Ancient castles used stone firewalls to prevent fires from spreading.
You should firewall your home network against cyberattacks.
The firewall blocked suspicious traffic from entering the server.
Modern buildings often integrate firewalls into their design for safety.