flat·line | \ˈflat-ˌlīn \
flatlined; flatlining; flatlines

Definition of flatline 

intransitive verb

1a : to register on an electronic monitor as having no brain waves or heartbeat

b : die

2a : to be in a state of no progress or advancement

b : to come to an end

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Other Words from flatline

flatliner noun

Examples of flatline in a Sentence

the patient was fading fast, and doctors expected him to flatline before the night was over

Recent Examples on the Web

Nic Budden, Foxton’s CEO, predicts that the real estate market will remain challenging this year, while Samuel Tombs, analyst at Pantheon Economics, predicts that house prices will flatline for the next 6 months. Washington Post, "2 years on, Brexit vote has taken a toll on UK economy," 23 June 2018 University of Washington modeling, commissioned by Gates, estimates that if investment isn't increased in health and education, then the per-capita GDP, rising steadily for decades, will flatline. David Mckenzie, CNN, "Bill Gates tells Nigerian leaders to 'face facts' so they can make progress," 26 Mar. 2018 Average house prices, then, look set to flatline this year. Samuel Tombs, WSJ, "Britain’s New Housing Dilemma," 7 Mar. 2018 Berman said campaigns typically flatline in the middle. Cheryl V. Jackson, chicagotribune.com, "Chicago design veteran winds up in a 'nail biter' on Kickstarter," 7 Sep. 2017 The inning would flatline in the next moments when Cuthbert bobbled a grounder at third base and threw wildly to first, allowing another run to score and everybody to be safe. Rustin Dodd, kansascity.com, "Shaky relief corps, tight strike zone doom Royals in 8-2 loss to Blue Jays," 25 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'flatline.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of flatline

1980, in the meaning defined at sense 1a

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Dictionary Entries near flatline

flat knot






flat machine

Statistics for flatline

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Time Traveler for flatline

The first known use of flatline was in 1980

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More Definitions for flatline

flat·line | \ˈflat-ˌlīn \
flatlined; flatlining

Medical Definition of flatline 

1 : to register on an electronic monitor as having no heartbeart or brain waves : to experience cessation of heart contractions or brain wave activity as indicated by a flat line on a electrocardiogram or electroencephalogram I flatlined on the operating table, but Dr. Bunsom managed to revive me.— Alison Wright, Yoga Journal, May/June 2005 He used to be ill quite a bit as a younger child, and his heart flatlined four times before he was 6.— Ginnie Graham, Tulsa World, 19 Dec. 2007

2 : die entry 1 But just because death is expected doesn't mean it's any less depressing when the patient finally flatlines.— Phil Taylor, Sports Illustrated, 26 Jan. 2009

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Comments on flatline

What made you want to look up flatline? Please tell us where you read or heard it (including the quote, if possible).


to reject or criticize sharply

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