Plain and plane get confused all the time. Probably because they sound the same, come from the same Latin word, and spelling them for the correct usage is often tricky. Oh, and they have a couple of similar meanings, which makes things even worse! So, let's start with the basics. Something plain is simple and ordinary. A plane is what you see flying in the sky. It’s also a tool to shape and smooth wood.
The word plain comes from the Latin word planus, meaning "flat or level." Its most basic meaning describes things that are simple and uncomplicated — think plain bagel or the plain explanation that makes something clear to you. Another very common meaning of plain is "flat, open land," which is also simple and bare — think miles and miles of grass without trees and hills. Plain is also an adverb that means "unmistakably" because simple, clear things or qualities are obvious. Check out these examples that illustrate the different uses of plain:
She was dressed in a plain brown skirt and white blouse. (Walk Two Moons)
The surface of the plain is only sand and gravel, as far as the eye can reach. (Crossing the Plains)
Now she was confused, now she was just plain scared. (The Westing Game)
Plane, which comes from the Latin planus as well, can also describe a flat surface. However, plane is mainly used for two-dimensional surfaces, not landforms. In geometry, a plane can only be a flat area or shape. A carpenter’s plane makes wood surfaces flat and smooth. And, the plane you fly in moves along a flat, level, and smooth path up in the air. Look at these smooth examples of plane in action:
But in the eleventh grade, I got good scores in plane geometry from the start. (October Sky)
It took weeks before Clancy mastered how to use a plane to make a completely flat piece of wood. (Washington Times)
Plain things are simple and ordinary. Plane surfaces are even and level. And when you make a plan to get on a plane, you’ve just added an e to your plan. Safe travels!The plane lifted its nose and rose into the air. (Eleven)