Other forms: plowshares
A plowshare is a steel blade that cuts the top layer of soil. It's part of a plow.
A plowshare is an important part of a plow: you might call it the business end, because it's the part that does the cutting of grass and soil. There are many types of plows, including mechanical plows, riding plows, and handheld blows, but the blade of all of them can be called a plowshare. This word is part of a famous proverb about "beating swords into plowshares," which means to move from war to peace. Plowshare is often spelled ploughshare.