Breastplate (2382) (thorax) describes either the chest area or part of the body covered by the breastplate or the protective covering of this area as utilized in combat. Polybius tells us that it was known as a heart-protector. Usually it was made of bronze but the more affluent officers wore a coat of chain mail. The front piece was strictly the breastplate, but a back piece was commonly worn as well. Isaiah prophetically describes Messiah wearing the breastplate of righteousness, recording (in the context of a tragic description of sins by Israel) that... He (Messiah) put on righteousness like a breastplate, and a helmet of salvation on His head; and He put on garments of vengeance for clothing, and wrapped Himself with zeal as a mantle. 18 According to their deeds, so He will repay, wrath to His adversaries, recompense to His enemies. To the coastlands He will make recompense. 19 So they will fear the name of the LORD from the west and His glory from the rising of the sun, For He will come like a rushing stream, which the wind of the LORD drives. (Isaiah 59:17, 18, 19) Comment: This prophecy is a picture of Messiah's second advent, at the end of the Great Tribulation, to save those who will be saved and to judge those who rejected His salvation. Had our Substitute not been fully, perfectly righteous, we could never have attained God's required righteousness. Instead Paul explains that believers have nothing to boast it for by God's "doing you are in Christ Jesus, who became to us wisdom from God, and righteousness and sanctification, and redemption" 1Cor 1:30. Thayer describes the armor writing that it was... a breast-plate or corselet consisting of two parts and protecting the body on both sides from the neck to the middle (Homer, Herodotus, Xenophon, Plato, others): There are 10 uses of thorax in the Septuagint (LXX) (1 Sam. 17:5; 1 Ki. 22:34; 2 Chr. 18:33; 26:14; Neh. 4:16; Job 41:13, 26; Isa. 59:17; Jer. 46:4; Ezek. 38:4). Isaiah 59:17 And He put on righteousness like a breastplate (LXX = thorax), and a helmet of salvation on His head; and He put on garments of vengeance for clothing, and wrapped Himself with zeal as a mantle. TDNT - In Greece we find various forms of armor from leather doublets (with metal studs) to bronze armor conforming to the body. The Romans also use coats of mail combining lightness and strength. Armor comes into Egypt from abroad. Goliath the Philistine wears a heavy coat of mail. In Israel armor is at first a privilege of the nobility but comes into general use under Uzziah...The OT. The biblical metaphor originates in Isaiah 59:17 (see above) with its statement that God has put on righteousness like a breastplate, i.e., that He will deploy His full moral integrity to destroy evil and bring salvation in the sense both of justice (Kittel, G., Friedrich, G., & Bromiley, G. W. Theological Dictionary of the New Testament. Eerdmans) There are 5 uses of thorax in the NAS... Ephesians 6:14 Stand firm therefore, having girded your loins with truth, and having put on the breastplate of righteousness, 1 Thessalonians 5:8 But since we are of the day, let us be sober, having put on the breastplate of faith and love, and as a helmet, the hope of salvation. Revelation 9:9 And they had breastplates like breastplates of iron; and the sound of their wings was like the sound of chariots, of many horses rushing to battle. Revelation 9:17 And this is how I saw in the vision the horses and those who sat on them: the riders had breastplates the color of fire and of hyacinth and of brimstone; and the heads of the horses are like the heads of lions; and out of their mouths proceed fire and smoke and brimstone.