WordReference Random House Unabridged Dictionary of American English © 2026
third′ rail′, [Railroads.]
- Rail Transporta rail laid parallel and adjacent to the running rails of an electrified railroad to provide electric current to the motors of a car or locomotive through contact shoes.
- Rail Transportan additional running rail laid on the same ties as the two regular rails of a railroad track to provide a multigauge capability.
- 1865–70, American.
'third rail' also found in these entries (note: many are not synonyms or translations):