- To refuse home mortgages or home insurance to areas or neighborhoods deemed poor financial risks.
- To reach the maximum engine speed at which an engine is designed to be safely operated: The car redlined at 80 miles per hour in fourth gear.
- Computer Science To mark or highlight edited text, as with a red line, to distinguish it from unedited portions of a document.
- To discriminate against by refusing to grant loans, mortgages, or insurance to.
- To remove from operational status because of mechanical defects or the need for scheduled maintenance: redlined three fighter aircraft.
- Computer Science To mark (edited text) by redlining.
- A safety limit, as marked on a gauge.
- Sports The red line at the center of an ice hockey rink, running parallel to the goal lines and dividing the rink in half.
- Sports Either of two red lines running across an ice hockey rink near the end boards, in the center of which the goal is positioned.