cataphract (n.)

1580s, "scale-like metal armor for the body," from Latin cataphractes "breastplate of iron scales," from Greek kataphraktes "coat of mail," from kataphraktos "mailed, protected, covered up," from kataphrassein "to fortify," from kata "entirely" (see cata-) + phrassein "to fence around, enclose, defend" (see diaphragm). From 1670s as "a soldier in full armor" (probably from Latin cataphracti "mailed soldiers"). Related: Cataphractic.