ARAC:
This tight-fitting cuirass
Is but a useless mass,
It's made of steel
And weighs a deal,
A man is but an ass
Who fights in a cuirass,
So off goes that cuirass.Princess Ida — W.S. Gilbert
Basic Information
A cuirass is a piece of plate armour consisting, effectively, of a breastplate and backplate joined together, normally at the shoulders and under the arms, giving all-round protection to the torso (and generally the abdomen as well). The resulting piece is obviously more protective that simply wearing a breastplate, but also less flexible and more encumbering.
The cuirass was amongst the last pieces of plate armour to become extinct - and indeed is still on ceremonial issue in a number of armed forces around the world.
Arguably the name could be applied to any form of rigid or semi-ridgid armour covering the relevant areas - lorica segmenta is often referred to as a cuirass in its popular incarnations.