flatline
verb
flat·line
ˈflat-ˌlīn 
flatlined; flatlining; flatlines
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
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
Every time the plot hits the reset button, the tension flatlines.
—
Justin Chang, New Yorker, 14 Oct. 2025
Fanning flatlines when left to be a solo show as Bertino whacks her around like a pinball, hitting big, loud scares that seem to keep resetting.
—J. Kim Murphy, Variety, 11 Oct. 2025
After flipping a first-possession interception by linebacker Zack Baun into a short-field touchdown, the Eagles offense flatlined under first-time offensive coordinator Kevin Patullo.
—Brooks Kubena, New York Times, 22 Sep. 2025
After administering chest compressions — during which Bennett flatlined — a doctor asked if the couple would be willing to put their son on life support.
—Greta Bjornson, PEOPLE, 21 Sep. 2025
See All Example Sentences for flatline
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Justin Chang, New Yorker, 14 Oct. 2025
Fanning flatlines when left to be a solo show as Bertino whacks her around like a pinball, hitting big, loud scares that seem to keep resetting.
—J. Kim Murphy, Variety, 11 Oct. 2025
After flipping a first-possession interception by linebacker Zack Baun into a short-field touchdown, the Eagles offense flatlined under first-time offensive coordinator Kevin Patullo.
—Brooks Kubena, New York Times, 22 Sep. 2025
After administering chest compressions — during which Bennett flatlined — a doctor asked if the couple would be willing to put their son on life support.
—Greta Bjornson, PEOPLE, 21 Sep. 2025
See All Example Sentences for flatline
Cite this Entry
“Flatline.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/flatline. Accessed 18 Oct. 2025.
Copy CitationMedical Definition
flatline
intransitive verb
flat·line
ˈflat-ˌlīn
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
Alison Wright, Yoga JournalHe 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
Ginnie Graham, Tulsa World2
: 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
Phil Taylor, Sports IllustratedLove words? Need even more definitions?
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