flatline

verb

flat·​line ˈflat-ˌlīn How to pronounce flatline (audio)
flatlined; flatlining; flatlines
Synonyms of flatlinenext

intransitive verb

1
a
: to register on an electronic monitor as having no brain waves or heartbeat
b
: die
2
a
: to be in a state of no progress or advancement
b
: to come to an end
flatliner noun

Synonyms of flatline

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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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Surprisingly, OpenAI’s overall usage within enterprises completely flatlined from about October 2025 to December 2025. — Emily Forlini, Fortune, 13 Aug. 2026 In the middle of all of this, after several Housewives franchises have been flatlining in recent years, a new addition has breathed life into the format and quickly garnered fans. — Mia Galuppo, HollywoodReporter, 12 Aug. 2026 Experts fear that surging Chinese overcapacity — stoked by flatlining domestic consumption — could further deepen the EU-China trade imbalance. — Mohammed Sergie, semafor.com, 29 July 2026 Enrollment is declining across the board in traditional public schools as the national birthrate continues to fall, charter school enrollment remains robust, private school voucher use increases and the number of immigrant students has flatlined. — Austin Horn july 3, Miami Herald, 3 July 2026 See All Example Sentences for flatline

Word History

First Known Use

1980, in the meaning defined at sense 1a

Time Traveler
The first known use of flatline was in 1980

Rhymes for flatline

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Browse Nearby Words

flatlet
flatline
flatling
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Cite this Entry

“Flatline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/flatline. Accessed 15 Aug. 2026.

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Medical Definition

flatline

intransitive verb
flat·​line ˈflat-ˌlīn How to pronounce flatline (audio)
flatlined; flatlining
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
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
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
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