Third rail meaning

What does the saying 'Third rail' mean?

Idiom: Third rail

Meaning: The third rail of something is dangerous to alter or change. Originally, the third rail is the one carrying the electricity for a train.

Country: International English | Subject Area: General | Usage Type: Both or All Words Used
All idioms have been editorially reviewed, and submitted idioms may have been edited for correctness and completeness.

If you have a question about idioms, ask us about it in our Idioms Discussion Forum.

If you know of an idiom that you would like to be listed here, please use our online form to suggest an idiom.

See also:


Trustpilot