CUIRASS (Fr. cuirasse, Lat. coriaceus, made of leather, from corium, the original breast-plate being of leather), the plate armour, formed of one or more pieces of metal or other rigid material which covers the front of the wearer's person (see ARMS and ARMOUR). In a suit of armour it was generally worn in con nection with a corresponding defence for the back and is under stood to imply the complete body-armour, described in the middle ages as a "pair of plates." The corselet (Fr. corselet, diminutive of the O.Fr. cors, body), a comparatively light cuirass, is more strictly a breast-plate only. As parts of the military equipment of classic antiquity, cuirasses and corselets of bronze and of other rigid substances were common, but while some special kind of secondary protection for the breast had been worn in earlier times in addition to hauberks and studded "cotes" it was not until the r4th century that a regular body-defence of plate was adopted. From that time the cuirass came into general use as well as plate coverings for the limbs, and by the end of the century had superseded the familiar chain-mail. In the early r 5th century entire plate armour began to be worn without any surcoat, but toward its end the short surcoat or "tabard" came into general use over the armour. At this time small plates of various shapes and sizes (and not always in matching pairs) were attached to the armour in front of the shoulders to defend these vulnerable points. In the middle of the century the breast-plate of the cuirass was made in two parts, the lower overlapping the upper and con trived, by means of a strap or sliding rivet, to give flexibility. Later the cuirass was sometimes superseded by the "brigandine jacket," made generally of a rich textile lined throughout with overlapping metal scales riveted on with studs also of metal. In the i 6th century the cuirass, with globular breast-plate, was reinforced by strong additional plates attached by rivets or screws. In about 155o the breast-plate of the cuirass was characterized by a vertical central ridge, called the "tapul," having near its centre a projecting point; this projection, somewhat later, was lowered to the base of the plate and assumed the form which was known as the "peascod cuirass." Corselets provided with both breast and back pieces were worn by foot-soldiers in the i 7th century, while their mounted comrades were equipped with heavier and stronger cuirasses. These de fences continued in use after the other pieces of armour had gradually been discarded, and their use has never altogether ceased. In modern armies mounted cuirassiers have in some degree perpetuated the character of the mediaeval body-armour although the steel-jacketed bullet of present-day warfare has demonstrated the futility of light metal-plate armour as a means of body protection.