The musket's etymology traces one of the most entertaining metaphorical chains in the history of weaponry: from fly to hawk to crossbow bolt to firearm. The word enters English from French mousquet, borrowed from Italian moschetto, which was originally the diminutive of mosca (fly), from Latin musca (fly).
The chain works as follows: Italian moschetto first meant a young male sparrowhawk — literally a 'little fly-catcher,' the hawk that hunts flies and other small prey. The name was then transferred to a type of crossbow bolt, perhaps because the bolt flew toward its target like a hawk diving on prey. When the firearm was developed as a replacement for the crossbow in the early 16th century, the crossbow bolt's name transferred to the new weapon.
This etymological chain — insect to predator to projectile to weapon — is well-documented but still remarkable. The musket, one of the most important weapons in military history, carries hidden within its name a miniature natural history of predation.
The musket transformed warfare between the 16th and 19th centuries. As a smoothbore, muzzle-loading weapon firing a lead ball, the musket was inaccurate at distances beyond about 100 meters but devastatingly effective in massed volleys. Military tactics evolved around the musket's capabilities and limitations: the line formation, the volley fire system, and the bayonet charge all developed to maximize the musket's effectiveness.
Dumas's The Three Musketeers (Les Trois Mousquetaires, 1844) ensured the word's literary immortality, though the novel's heroes actually fight primarily with swords. The Musketeers of the Guard were an elite French military company, and their name — derived from their original armament — stuck even as their tactical role evolved beyond musket warfare.
The musket was rendered obsolete by the rifle — a firearm with spiral grooves (rifling) cut into the barrel, which spun the projectile and dramatically improved accuracy. The transition from musket to rifle, completed by the mid-19th century, made the old line-formation tactics suicidal and forced a complete reimagining of warfare.
The word mosquito — the biting insect — shares the same Latin root musca. Musket and mosquito are thus etymological cousins: the weapon and the pest both named, ultimately, for the common fly.