redline

American

[red-lahyn, red-lahyn] / ˈrɛdˌlaɪn, ˈrɛdˈlaɪn /

Or red-line

verb (used with object)

redlined, redlining

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.

verb (used without object)

redlined, redlining

to engage in redlining.

noun

Automotive.
1. the maximum rotational speed, or angular velocity, of the engine crankshaft that is considered safe: often measured in rpm.
2. a red line or boundary of a red area that delineates such a value, as on a tachometer.

redline British

/ ˈrɛdˌlaɪn /

verb

(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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

redliner noun

Etymology

Origin of redline

First recorded in 1940–45; red ¹ + line ¹

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

This innovation goes back a ways, to Enzo Ferrari himself, who decreed that the power in his cars should always rise, linearly and proportionally, with throttle demand, from low revs to redline.

From The Wall Street Journal • Oct. 23, 2025

Kazakhstan's Rybakina, whose power from the baseline is among the very best when she finds her groove, continued to redline in the second set.

From BBC • Aug. 29, 2025

A lone rider leaves the redline at Union Station.

From Los Angeles Times • Jun. 20, 2025

“AI must be guided in a direction that is conducive to the progress of humanity, so there should be a redline in AI development — a red line that must not be crossed,” without elaborating.

From Seattle Times • Jan. 18, 2024

They were past redline now, flying at 220 miles per hour and in danger of ripping the plane’s wings off.

From "Mountain of Fire" by Rebecca E. F. Barone

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023