flatlined; flatlining; flatlines
Definition of flatline
1a
: to register on an electronic monitor as having no brain waves or heartbeat
b
: die
2a
: to be in a state of no progress or advancement
b
: to come to an end
Keep scrolling for more
Keep scrolling for more
Keep scrolling for more
Test Your Vocabulary
The Exceptions Quiz III
-
- Which of these words does not mean "nonsense"?

Test your vocabulary with our 10-question quiz!
TAKE THE QUIZ
A daily challenge for crossword fanatics.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridged
Words at Play
Ask the Editors
Share flatline
Time Traveler for flatline
The first known use of flatline was in 1980
See more words from the same year