red line

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.

red line

noun

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

Word History and Origins

Origin of red line¹

First recorded in 1960–65

Example Sentences

Biden has committed tens of billions of dollars to Kyiv's war effort, and at the weekend he reportedly ditched a long-standing red line on Ukraine's use of American weaponry to launch attacks deep into Russia.

From BBC

China says its claim to the self-ruling island is a red line.

From BBC

"No one should be compelled, for example, to take part in assisted dying if they've got moral or ethical objections as clinicians. That certainly would be one of my red lines".

From BBC

For more than a year Israel has crossed most of America’s red lines.

From BBC

“By setting red lines and allowing Netanyahu to cross them without consequence, the Biden administration effectively encouraged further impunity. I don’t think any of this will change in the next 10 weeks,” he said.

From BBC