third rail
noun/ˌθɜːd ˈreɪl/
/ˌθɜːrd ˈreɪl/
- an extra metal bar next to or between the tracks of a railway that provides electricity to the trains
- Subway trains draw direct current from the third rail to power their motors.
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- (North American English, informal) a subject that politicians think is too sensitive and likely to offend people or cause them to angrily disagree and so is not discussed
- Social security has long been considered a third rail of US politics.
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third rail