cuirasse

French cuirasse came from Late Latin coriacea (vestis), meaning a leather (garment), from corium (leather, hide). The earliest cuirasses were indeed leather — hardened, boiled, sometimes reinforced with metal plates. Roman lorica was typically leather or linen with metal reinforcement. The word cuirass entered English in the fifteenth century, by which time the armor it named had transitioned almost entirely to metal. The leather word described a steel object.

The full cuirass — breastplate and backplate — was the core of a knight's armor. Everything else attached to or worked around the torso protection. As firearms improved, armor was simplified. By the seventeenth century, cavalrymen wore a cuirass and a helmet but little else — the rest had been abandoned as too heavy for the diminishing protection it offered. Cuirassier regiments became a distinct cavalry type, named for their chest armor.

Napoleon's cuirassiers were among the most famous heavy cavalry units in history. At Waterloo in 1815, cuirassier charges broke against British infantry squares. The armor offered some protection against sabers and spent musket balls but not against point-blank volleys. The cuirass was becoming ceremonial even as it remained regulation equipment. French cuirassiers wore polished steel breastplates into World War I, in 1914, before the reality of modern weapons forced them to dismount.

Modern body armor — Kevlar vests, ceramic plates — is the cuirass reborn in synthetic materials. The function is identical: protect the torso from projectiles. The word cuirass is not used for modern armor, but the concept is the same. A Roman legionary's leather cuirass, a medieval knight's steel cuirass, and a modern soldier's ballistic plate carrier all do the same job. The material changes. The word remembers the leather.