red line

American  

noun

1. Ice Hockey. a line of the color red that is parallel to and equidistant from the goal lines and divides the rink in half.

2. a limit, point, or boundary beyond which one may not go without incurring negative consequences.

   The use of chemical weapons is a red line, which, if crossed, could trigger military action.

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red line British  

noun

1. a point beyond which a person or group is not prepared to negotiate

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Etymology

Origin of red line

First recorded in 1960–65

Example Sentences

See Examples For:

red line

One red line Meta didn’t cross—barely—was the border into negative free cash flow.

From The Wall Street Journal ● Jul. 30, 2026

The shop had already said before the raid that it would close in August, citing the social environment, its financial situation and "the elusive red line".

From Barron's ● Jul. 29, 2026

And with nominal yields, real yields, global rates and term premiums all moving in the same direction, a 5.2% yield is now the bright red line investors should watch.

From MarketWatch ● Jul. 24, 2026

Ancelotti said that Neymar would only be called up if he deserved the place, that he would not take any injured players - and broke every red line for Neymar.

From BBC ● Jul. 6, 2026

The sole is bulging and dark, with a red line running around the edge.

From "Water for Elephants" by Sara Gruen