1. to show no electrical activity on a medical monitor, indicating death or cardiac arrest
Usage: medical
2. to show no activity, progress, or change; to remain completely level or static
Usage: figurative

Examples

• The patient flatlines during surgery but is successfully revived.
• His heart monitor flatlines for several seconds.
• The economy flatlines with no growth for months.
• Sales have been flatlining since the new competitor entered the market.
• The stock price flatlines after the disappointing earnings report.
• Her career flatlines after the scandal breaks.