(1.) That piece of ancient armour that protected the breast. This word is used figuratively in Ephesians 6:14 and Isaiah 59:17. (see ARMOUR.)

(2.) An ornament covering the breast of the high priest, first mentioned in Exodus 25:7. It was made of embroidered cloth, set with four rows of precious stones, three in each row. On each stone was engraved the name of one of the twelve tribes (Exodus 28:15-29; 39:8-21). It was in size about ten inches square. The two upper corners were fastened to the ephod by blue ribbons. It was not to be "loosed from the ephod" (Exodus 28:28). The lower corners were fastened to the girdle of the priest. As it reminded the priest of his representative character, it was called the memorial (28:29). It was also called the breastplate of judgment (28:15). (see PRIEST.)

Noah Webster's New International Dictionary of the English Language

1. (n.) A plate of metal covering the breast as defensive armor.

2. (n.) A piece against which the workman presses his breast in operating a breast drill, or other similar tool.

3. (n.) A strap that runs across a horse's breast.

4. (n.) A part of the vestment of the high priest, worn upon the front of the ephod. It was a double piece of richly embroidered stuff, a span square, set with twelve precious stones, on which were engraved the names of the twelve tribes of Israel. See Ephod.