What does the word breastplate mean?

Usage examples for breastplate

  1. My heart beats wildly, Gorgo; it is well that this breastplate holds it fast, for I feel as though it would burst with hope and thankfulness." – The Complete Historical Romances of Georg Ebers by Georg Ebers
  2. To that breastplate, Pier, beat it out for us fine and true: iron well beaten is proof against bullets. – Flemish Legends by Charles de Coster