# Plane or Plain?

Our Story

## Plane or Plain?

What is the difference between "plane" and "plain"?
• "Plane" usually means an airplane, a flat surface, or a tool for shaving wood. For example:
• "Plain" usually means simple or an expanse of lowland. For example:

## More about "Plane" and "Plain"

The words "plane" and "plain" have several meanings. Unfortunately, both have a meaning relating to flatness, and this is often the source of confusion.

## Plain

The word "plain" has three main meanings:

(1) Simple (i.e., not elaborate).
• a plain girl
• a plain cake
• a plain colour
(2) Apparent.
• It is plain to see.
• It seems quite plain to me.
Plain is an adjective in these examples.

(3) An expanse of level and low land.
• The Russian Plain.
• I joined the Chinese farmers as they attempted to drive the yaks across the plain in western China.
Plain is a noun in these examples.

## Plane

The word "plane" has six main meanings:

(1) An airplane.
• What time is your plane?
Do you say "airplane" or "aeroplane"?

(2) A flat surface (especially in mathematics).
• In a 3D space, a plane can be defined by specifying a point and a normal vector to the plane.
(3) A level (usually figurative).
• I was hoping for a conversion on a higher plane.
(4) A tool for smoothing or shaping wood (i.e., a carpenter's plane).

(5) To shave wood into shape.
• Can you plane a few inches off the top of the door?
(6) To travel on the surface of water.
• The car hit the puddle and planed straight into the back of the lorry.
• (This is also known as "to aquaplane.")
Planes Are above Ground

Confusion arises mostly between "plain" meaning expanse of lowland and "plane" meaning a flat surface or a level.

A plain (lowland) is always on the ground. A plane (a surface or a level) is nearly always above the ground...like an airplane.

Therefore, if it's above the ground, it's almost certainly "plane."
##### Interactive Exercise
Here are three randomly selected questions from a larger exercise, which can be edited, printed to create an exercise worksheet, or sent via email to friends or students.