the.com/emergency flare

means A bright burning signal device used to mark your location or signal distress when you need rescue or attention fast.

from 'Flare' as 'sudden burst of light' emerged in the 1600s-1700s, likely echoing the flaring, spreading motion of flame or cloth catching wind — the sense of something flaring up and out. By the 1800s sailors and signal-makers had turned that flare into a noun for a device: a flame or light built specifically to be seen from a distance. 'Emergency' comes from Latin emergere, 'to rise up or come forth' — literally what you want someone to do for you when you're stranded. Put together, the phrase is 19th-century practical English: a thing that flares, for when trouble emerges.