0 a limit beyond which someone's behaviour is no longer acceptable:
It has been said that, rather than cross the red line, it was better for the negotiations to fail, and that is what happened.
There is the red circle on the white ground with a turn right in black which has been crossed out with a red line.
He referred to the "thin red line"; he now claims that the second battalion is the successor to the "thin red line".
Previously, we were told that that was a red line that they would not concede.
In that sense, you could say that we who oppose the banning are holding a thin red line.
I have every reason to believe that the "thin red line" will very soon be back at their stations.
The external financing limits have proved to be a thin red line, constantly breached.
It will be a red line for us.
