Standard Lemma guide

flatline

noun · verb · 10 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.

  • /ˈflætˌlaɪn/
  • Australia: Recorded audio is listed in the source snapshot.

1

noun

Meaning 1

An asystole; the absence of heart contractions or brain waves.

The disappearance of the rhythmic peaks displayed on a heart monitor.

Definition source: English Wiktionary via Wiktextract

Topics: cardiology, medicine, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

An asystole; the absence of heart contractions or brain waves.

The disappearance of brain waves on an electroencephalogram.

Definition source: English Wiktionary via Wiktextract

Topics: cardiology, medicine, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

3

noun

Meaning 3

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

Definition source: English Wiktionary via Wiktextract

Usage: also, figuratively

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

4

noun

Meaning 4

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

Definition source: English Wiktionary via Wiktextract

Topics: fishing, hobbies, lifestyle

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

5

verb

Meaning 5

To stop beating.

Definition source: English Wiktionary via Wiktextract

Usage: intransitive

Topics: cardiology, medicine, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

6

verb

Meaning 6

To die.

Definition source: English Wiktionary via Wiktextract

Usage: broadly, intransitive

Topics: cardiology, medicine, sciences

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

7

verb

Meaning 7

To kill.

Definition source: English Wiktionary via Wiktextract

Usage: slang, transitive

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

8

verb

Meaning 8

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

Definition source: English Wiktionary via Wiktextract

Usage: informal, transitive

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

9

verb

Meaning 9

To experience significantly decreased rates of change compared to previous rates of change.

Definition source: English Wiktionary via Wiktextract

Examples

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

Meaning relationships

Synonyms: none provided

Antonyms: none provided

10

verb

Meaning 10

To fish using a flatline.

Definition source: English Wiktionary via Wiktextract

Usage: intransitive

Topics: fishing, hobbies, lifestyle

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

History

Etymology

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