moldboard(n = noun.artifact) mouldboard - wedge formed by the curved part of a steel plow blade that turns the furrow;
is a kind of wedge
is a part of moldboard plow, mouldboard plough
1. A curved plate of iron (originally of wood) back of the share of a plow, which turns over the earth in plowing. [1913 Webster]
2. A follow board. [1913 Webster]