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

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Example Sentences

See Examples For:

red line

"Protests are a right, whereas violence is a crime; this red line must be drawn clearly at this critical stage of our democratic development," Rama said in a Facebook post.

From Barron's ● Oct. 19, 2026

President Isaac Herzog called it the "crossing of a red line".

From BBC ● Aug. 30, 2026

Slavin’s crime, in his own account, was saying in a televised interview with CBS that censorship of news for service members would be a personal red line he would not cross.

From Salon ● Aug. 29, 2026

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

From The Wall Street Journal ● Jul. 30, 2026

Or a red line and a blue line.

From "The Woman All Spies Fear" by Amy Butler Greenfield

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