fourth rail
fourth rail · fourth rails
An extra rail in addition to the third rail which is used for current return purposes,…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.
Meaning
1 sensesAn 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.
Forms
plural: fourth rails| Singular | fourth rail |
|---|---|
| Plural | fourth rails |
regular