flat·​line | \ ˈflat-ˌlīn How to pronounce flatline (audio) \
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

Synonyms & Antonyms for flatline


check out, conk (out), croak [slang], decease, demise, depart, die, drop, end, exit, expire, fall, go, kick in [slang], kick off [slang], part, pass (on), pass away, peg out [chiefly British], perish, pop off, step out, succumb


breathe, live

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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

Advanced economies could flatline their emissions tomorrow and all would still be lost. David Roberts, Vox, "The climate change policy with the most potential is the most neglected," 11 July 2019 The anomalies could go the way of so many others detected in high-energy experiments, including some measured by LHCb in recent years, and flatline as more data accumulates. Quanta Magazine, "‘Penguin’ Anomaly Hints at Missing Particles," 20 Mar. 2015 If the large ships’ calls aren’t reduced, that growth will flatline or even decline, the coalition warns. Erica E. Phillips, WSJ, "Fight Brews in Houston’s Port Over Energy Exports," 19 Dec. 2018 Other third-party data suggests that Lyft’s growth rate will flatline compared to Uber. Andrew J. Hawkins, The Verge, "Lyft hits a major milestone: 1 billion trips," 18 Sep. 2018 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

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 How to pronounce flatline (audio) \
flatlined; flatlining

Medical Definition of flatline

1 : to register on an electronic monitor as having no heartbeat 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).


a topic to which one constantly reverts

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