redline N. Amer.
informal
■ verb
1》 drive with (the car engine) at its maximum rpm.
2》 refuse (a loan or insurance) to someone due to their area of residence.
■ noun
1》 the maximum number of revolutions per minute for a car engine.
2》 a boundary or limit which should not be crossed.
Origin
from the use of red as a limit marker, in sense 2 of the noun a ring marking part of a map.