[ˈflatlʌɪn], (Verb)

Definitions:
- fail to increase; remain static
(e.g: their share of the vote has flatlined at about 3%)

- (of a person) die
(e.g: they injected themselves with a deadly drug and flatlined)


Phrases:

Origin:
1970s: from flat + line. flatline is a reference to the continuous straight line displayed on a heart monitor, indicating death