Easton's Bible Dictionary (1 Samuel 13:20, 21), an agricultural instrument, elsewhere called "ploughshare" (Isaiah 2:4; Micah 4:3; Joel 3:10). It was the facing-piece of a plough, analogous to the modern coulter. Noah Webster's Dictionary (n.) Same as Colter. Int. Standard Bible Encyclopedia COULTER kol'-ter. See PLOW.

Multi-Version Concordance Coulter (1 Occurrence) 1 Samuel 13:20 But all the Israelites went down to the Philistines, to sharpen every man his share, and his coulter, and his axe, and his mattock. (KJV JPS ASV YLT)