Definition of "redline" [redline]

• To refuse home mortgages or home insurance to areas or neighborhoods deemed poor financial risks. (verb-intransitive)
• 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. (verb-intransitive)
• Computer Science To mark or highlight edited text, as with a red line, to distinguish it from unedited portions of a document. (verb-intransitive)
• To discriminate against by refusing to grant loans, mortgages, or insurance to. (verb-transitive)
• To remove from operational status because of mechanical defects or the need for scheduled maintenance: redlined three fighter aircraft. (verb-transitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Microsoft Word has this this editing thing called redline/strikethrough or strikeout or something."
• "When we got back [from White House staff] this extensive edited version, called the redline, two days before we were supposed to submit the report to Congress on March 29, 2007, that paragraph was deleted."
• "But it blows them away in fuel consumption (17 / 25 mpg TDI, 14 / 19 mpg for the V-6 gasoline, 12 / 17 mpg for the V-8 FSI gasoline), and it performs much like the V-8 minus a little top end urge because the redline is a bit below 5,000 rpm."