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intr.v. flat·lined, flat·lining, flat·lines
1. To show a horizontal line on the monitor of an electrocardiogram or an electroencephalogram, indicating no electrical activity.
2. Informal To die.
Being or relating to an electrocardiogram or an electroencephalogram that indicates no electrical activity.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
flatlineAn informal term for the state of a person whose medical monitoring equipment shows a flat line rather than the normal peaks and troughs. Such a person has recently died or is very near to death.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005