fourth rails

A form of fourth rail — An extra rail in addition to the third rail (live rail) which is used for current return purposes, mainly by London Underground, because of problems caused by using the running rails for current return underground.

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Meanings

noun
  1. pluralplural of fourth rail
Cite this entry
APA

fourth rails. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/fourth%20rails

MLA

“fourth rails.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/fourth%20rails. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “fourth rails,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/fourth%20rails.

Source: fourth rails on Wiktionary, CC BY-SA 4.0.