noun
Meaning 1
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.
Definition source: English Wiktionary via Wiktextract
Topics: rail-transport, railways, transport
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided