flatline

verb

flat·​line ˈflat-ˌlīn 

flatlined; flatlining; flatlines

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

• 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

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

Trump’s office and retail properties mostly flatlined, and his new social-media venture bled cash, though his stake in the unprofitable business is still worth $1.9 billion. —Dan Alexander, Forbes, 7 Oct. 2024

When Harrison joined Villa, his aim was to put the academy back on an upward trajectory following a period of flatlining. —Jacob Tanswell, The Athletic, 22 July 2024

The company’s shipment growth to China flatlined year-on-year in the third quarter. —Arjun Kharpal, CNBC, 25 Oct. 2024

That’s enough oomph to resuscitate a flatlining iPhone 12 Pro at least three times. —Jen Murphy, Outside Online, 21 Oct. 2024

Word History

First Known Use

1980, in the meaning defined at sense 1a

Medical 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

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