off the rails

Suggesting the derailment of a locomotive.

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off the rails

1. (idiomatic) In an abnormal manner, especially in a manner that causes damage or malfunctioning.
2. (idiomatic) Insane.
3. (idiomatic) Off the intended path.
   • 2009 July 13, Ed Bentley, “Lenin 1, Tsar Nicholas 0 – but Sheremetyevo-3”, in Moscow News:

     ... but the plan came off the rails when infuriated Communists called it "ideological provocation" and warned against "kindling political confrontation

   • 2022 August 10, Mel Holley, “Network News: Question marks over TransPennine upgrade spending”, in RAIL, number 963, page 24:

     "The DfT appears to have put things on a firmer footing, but the path is littered with cautionary tales of transport projects that later went off the rails.

4. (idiomatic) Out of control.
   • 2009 July 10, Jenny Johnston, “You won't catch us going to rehab: So have the young stars of Harry Potter turned into superbrats?”, in Daily Mail:

     I reckon it's pretty astonishing that none of us did go off the rails. There really was no telling how any of us would deal with the pressures and the fame.

5. Used other than figuratively or idiomatically: see off,‎ rail.
   • 2024 February 21, “Safety changes recommended after train hits collapsed wall”, in RAIL, number 1003, page 19:

     The train did not come off the rails and nobody was injured.

• Most commonly used with the verb to go, but also with forms of to be, to come, etc.