Other forms: breastplates
A breastplate is armour worn across the chest. A steel breastplate, buckle on the breastplate, a dented breastplate.
It is the single most useful piece of armour there is, since it covers the heart and the lungs, which is why it survived long after the rest was abandoned — cavalry wore one into the twentieth century. A good one was curved to turn a blow aside rather than stop it.
1nounbreastplateArmour worn across the chest.
“The knight's breastplate saved him from the arrow.”
breastplate is armour.
Breast plus plate, in Middle English, replacing an Old English word for the same thing.
Middle English
brestplate
English, today
breastplate
From Middle English brestplate, equivalent to breast + plate. Displaced brēostbeorg.
Etymology from Wiktionary, CC BY-SA