fusee (n.)

also fusileer, 1670s, "soldier armed with a musket," from French fusilier "musket" (17c.), literally "piece of steel against which a flint strikes flame," from Old French fuisil, foisil "steel for striking fire; flint; whetstone; grindstone" (12c.), from Vulgar Latin *focilis (petra) "(stone) producing fire," from Latin focus "hearth," in Vulgar Latin "fire" (see focus (n.)). Retained by certain regiments of the British army that were formerly armed with fusils.

"combustible cord or tube for lighting an explosive device," also fuze, 1640s, from Italian fuso, literally "spindle" (the ignition device so called for its shape, because the originals were long, thin tubes filled with gunpowder), from Latin fusus "a spindle," which is of uncertain origin. Influenced by French cognate fusée "spindleful of hemp fiber," and obsolete English fusee "musket fired by a fuse," which is from French. Meaning "device that breaks an electrical circuit" is first recorded 1884, so named for its shape, but erroneously attributed to fuse (v.) because it melts.