noun
sternum; breastplate; plastron
Refers to the sternum in anatomy, a breastplate in armor, or a plastron in zoology (e.g., turtle shell). Context determines the specific meaning.
胸甲は胸の中央にある平らな骨です。
The sternum is a flat bone in the center of the chest.
中世の騎士は胸甲を身に着けていた。
Medieval knights wore a breastplate.
A turtle's plastron is the hard part on the ventral side.