A cuirass (kwᵻˈræs,_kjʊəˈræs; cuirasse, coriaceus) is a piece of armour that covers the torso, formed of one or more pieces of metal or other rigid material. The word probably originates from the original material, leather, from the French cuirace and Latin word coriacea. The use of the term "cuirass" generally refers to both the breastplate and the backplate pieces; whereas a breastplate only protects the front, a cuirass protects both the front and the back of the wearer.
In Hellenistic and Roman times, the musculature of the male torso was idealized in the form of the muscle cuirass or "heroic cuirass" (in French the cuirasse esthétique) sometimes further embellished with symbolic representation in relief, familiar in the Augustus of Prima Porta and other heroic representations in official Roman sculpture. As parts of the actual military equipment of classical antiquity, cuirasses and corsets of bronze, iron, or some other rigid substance were used. Secondary protection for the breast was worn in earlier times by men-at-arms in addition to mail hauberks and reinforced coats. It was not until the 14th century that the plate armour became an established part of medieval armour.
The Roman emperor Galba donned a cuirass just before he went to his death. Suetonius records in 12 Caesars that, "As [Galba] was offering sacrifice on the morning before he was killed, a soothsayer warned him again and again to look out for danger, since assassins were not far off. Not long after this he learned that Otho held possession of the camp, and when several advised him to proceed thither as soon as possible – for they said that he could win the day by his presence and prestige – he decided to do no more than hold his present position and strengthen it by getting together a guard of the legionaries, who were encamped in many different quarters of the city. He did however put on a linen cuirass, though he openly declared that it would afford little protection against so many swords.