Etymologically
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firewall

This is the current revision of this entry, as edited by bogdan on 1 November 2026 at 02:58. This address is a permanent link to this version.
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Pronunciation

  • UK: /ˈfaɪə.wɔəl/, /ˈfaɪ.əˌwɔːl/[1]
  • US: /ˈfaɪ(ə)ɹˌwɔl/, /ˈfaɪ(ə)ɹˌwɑl/[1]

Etymology

It is a compound from English fire + wall.[2][3] It is also spelled with a hyphen.[3]

Earliest recorded meaning

An unbroken line of flames forming a barrier, a wall of fire: 1578, in W. Hilton's translation of a sermon by Urbanus Regius, a sense the OED calls somewhat rare.[2]

Semantic evolution

The sense of a wall built to stop the spread of fire, especially one in a building that rises above the roof, is recorded from about 1666.[2] Etymonline dates this sense to 1851,[3] and Dictionary.com dates the word to 1750–60 and labels it an Americanism.[4] From 1907 the word was used figuratively for anything that protects a system or institution as a barrier.[2] In computing it came to mean hardware or software that blocks unauthorized access to or from a network: the OED's first record is from 1971,[2] while Etymonline dates the computer sense, originally figurative, to 1990 at the latest.[3] The verb followed: in aviation, to push a throttle fully open, towards the firewall between cockpit and engine (1958); in computing, to protect with a firewall (1984); and generally, to keep something separate or isolated (1999).[2]

Timeline

  • 1578 – a wall of flames.[2]
  • c. 1666 – a wall built to stop the spread of fire.[2] Etymonline dates this sense to 1851.[3]
  • 1907 – figuratively, a protective barrier around a system or institution.[2]
  • 1958 – verb, to open a throttle fully.[2]
  • 1971 – in computing, a system protecting a network from unauthorized access.[2] Etymonline dates the sense to 1990 at the latest.[3]
  • 1984 – verb, to protect with a firewall.[2]
  • 1999 – verb, to keep separate or isolated.[2]

Meanings

Noun

  1. A fireproof wall or partition built to stop a fire spreading from one part of a building, vehicle or aircraft to another.[5][6][2]
  2. (computing) A program or device that protects a computer or private network against unauthorized access from outside, as from the Internet.[5][6][2]
  3. (figurative) A barrier or safeguard that keeps something separate or protected.[2]

Verb

  1. (computing) To protect a computer or network with a firewall.[6][2]
  2. To keep something separate or isolate it.[2]
  3. (aeronautics) To open a throttle fully.[2]

References

  1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j k l m n o p q r s Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  5. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins
  6. ^ a b c The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt