redline

UK: /ˈrɛdˌlaɪn/

Collins Concise English Dictionary © HarperCollins Publishers::

redline / ˈrɛdˌlaɪn/ verb (transitive)

1. (esp of a bank or group of banks) to refuse a loan to (a person or country) because of the presumed risks involved

WordReference Random House Unabridged Dictionary of American English © 2026

red′ line′, [Ice Hockey.]

1. Sport a line of the color red that is parallel to and equidistant from the goal lines and divides the rink in half.

• 1960–65

red•line  (v. red′līn′;n. red′līn′), v., -lined, -lin•ing, n. 
v.t. 

1. to treat by redlining (an area or neighborhood).
2. to establish the recommended safe speed of (an airplane):
   The bomber is redlined at 650 miles an hour.
3. to draw a canceling red line through (an item on a list).
4. to mark or designate for cancellation, rejection, dismissal, or the like:
   club members redlined for unpaid dues.
5. Aeronautics to cause (an airplane) to be grounded.

v.i. 

6. to engage in redlining.

n. 

7. 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.

Also, red′-line′. 

• red¹ + line¹ 1940–45

red′lin′er, n.