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.