Final answer:
A 'planed' piece of lumber is one that has been smoothed by a machine called a planer, making the wood uniform in thickness and width, which is essential for construction projects.
Step-by-step explanation:
A planed piece of lumber is one that has had its surface made smooth. When lumber is rough-cut, it comes directly from the sawmill with a fairly coarse and unfinished surface. In order to be used for building or in fine woodworking, the wood needs to be planed. This involves running the rough lumber through a machine called a planer, which uses sharp blades to shave off the top layer, resulting in a smooth surface. Planing also makes lumber more uniform in thickness and width, which is essential for many construction projects. It's an important step in the woodworking process that transforms the lumber into a more usable, visually appealing material.