- to treat by redlining (an area or neighborhood).
- to establish the recommended safe speed of (an airplane): The bomber is redlined at 650 miles an hour.
- to draw a canceling red line through (an item on a list).
- to mark or designate for cancellation, rejection, dismissal, or the like: club members redlined for unpaid dues.
- to cause (an airplane) to be grounded.
- to engage in redlining.
- Automotive.
- the maximum rotational speed, or angular velocity, of the engine crankshaft that is considered safe: often measured in rpm.
- a red line or boundary of a red area that delineates such a value, as on a tachometer.
- a line of the color red that is parallel to and equidistant from the goal lines and divides the rink in half.
- 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.
- (esp of a bank or group of banks) to refuse a loan to (a person or country) because of the presumed risks involved
- to restrict people's access to goods or services on the basis of the area in which they live
- a point beyond which a person or group is not prepared to negotiate
