flatline meaning: definition, etymology and quotations

flatline

noun

/ˈflætˌlaɪn/

Etymology From flat + line. Refers to a continuous straight line (asystole) on an ECG (EKG) or EEG, indicating death.

› An asystole; the absence of heart…

Cardiology, Medicine, Sciences The disappearance of the rhythmic peaks displayed on a heart monitor.

Cardiology, Medicine, Sciences The disappearance of brain waves on an electroencephalogram.

When brain function ceases, the electroencephalogram shows flatline recordings.1972, Louis Lasagna, “Aging and the field of medicine”, in Matilda White Riley, Anne Foner, editors, Aging and Society: Aging and the professions, page 68:

Also, Figuratively An unchanging state, as indicated in a graph of a variable over time.

Thus, you hear words like "flatline recession," "improvement at a greatly reduced rate," "economic hiccup," "recessionette," "rolling readjustment" and "the economy is double clutching."1967 June 17, “Business Outlook”, in Business Week, part 6, page 23:

Fishing, Hobbies, Lifestyle A line that is run low to the water from the rod tip, generally off a release clip of some type.

verb

Etymology From flat + line. Refers to a continuous straight line (asystole) on an ECG (EKG) or EEG, indicating death.

Cardiology, Medicine, Sciences Of the heart To stop beating.

Cardiology, Medicine, Sciences Broadly To die.

Slang To kill.

If looks could kill, Mona's sharp gaze would have flatlined him in one second.2013, Shobha Nihalani, Nine:
After all she'd been through, she needed sleep and food to heal, not endure a lovemaking session that was so passionate that it had pretty much flatlined him as well.2017, Stephanie Rowe, Not Quite Dead:

Informal To remain at the same level, without development; or, to fall.

The economy in Northern Ireland is flatlining and jobs are scarce.2012, The Guardian, National Trust attempts to block £100m Giant's Causeway golf course:
But passenger numbers have since recovered to only 85% of pre-March 2020 levels, and growth has flatlined.2022 November 16, Mel Holley, “Network News: West Midlands prioritises the return of passsengers”, in RAIL, number 970, page 24:

Of a graph To experience significantly decreased rates of change compared to previous rates of change.

Upon upload, the video got 1,000 views/day for the first week, then flatlined and started getting fewer than ten views/day.

Fishing, Hobbies, Lifestyle To fish using a flatline.