plane

¹ American  

[pleyn] / pleɪn /

noun

1. a flat or level surface.

2. Geometry. a surface generated by a straight line moving at a constant velocity with respect to a fixed point.

3. Fine Arts. an area of a two-dimensional surface having determinate extension and spatial direction or position.

   oblique plane; horizontal plane.

4. a level of dignity, character, existence, development, or the like.

   a high moral plane.

   Synonyms:

   stage, stratum

5. Aeronautics.

   1. an airplane or a hydroplane.

      to take a plane to Dallas.

   2. a thin, flat or curved, extended section of an airplane or a hydroplane, affording a supporting surface.

6. Architecture. a longitudinal section through the axis of a column.

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adjective

1. flat or level, as a surface.

   Synonyms:

   flush, even, smooth

2. of or relating to planes or plane figures.

verb (used without object)

planed, planing

1. to glide or soar.

2. (of a boat) to rise partly out of the water when moving at high speed.

3. Informal. to fly or travel in an airplane.

   We'll drive to Detroit and plane to Los Angeles.

plane ² American  

[pleyn] / pleɪn /

noun

1. Carpentry. any of various woodworking instruments for paring, truing, or smoothing, or for forming moldings, chamfers, rabbets, grooves, etc., by means of an inclined, adjustable blade moved along and against the piece being worked.

2. a trowellike tool for smoothing the surface of clay in a brick mold.

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verb (used with object)

planed, planing

1. to smooth or dress with or as if with a plane or a planer.

2. to remove by or as if by means of a plane (usually followed by away oroff ).

verb (used without object)

planed, planing

1. to work with a plane.

2. to function as a plane.

plane ³ American  

[pleyn] / pleɪn /

noun

1. plane tree.

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plane ¹ British  

/ pleɪn /

noun

1. See plane tree

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plane ² British  

/ pleɪn /

noun

1. maths a flat surface in which a straight line joining any two of its points lies entirely on that surface

2. a flat or level surface

3. a level of existence, performance, attainment, etc

4. 1. short for aeroplane

   2. a wing or supporting surface of an aircraft or hydroplane

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adjective

1. level or flat

2. maths (of a curve, figure, etc) lying entirely in one plane

verb

1. to fly without moving wings or using engines; glide

2. (of a boat) to rise partly and skim over the water when moving at a certain speed

3. to travel by aeroplane

plane ³ British  

/ pleɪn /

noun

1. a tool with an adjustable sharpened steel blade set obliquely in a wooden or iron body, for levelling or smoothing timber surfaces, cutting mouldings or grooves, etc

2. a flat tool, usually metal, for smoothing the surface of clay or plaster in a mould

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verb

1. to level, smooth, or cut (timber, wooden articles, etc) using a plane or similar tool

2. (often foll by off) to remove using a plane

plane Scientific  

/ plān /

1. A two-dimensional surface, any two of whose points can be joined by a straight line that lies entirely in the surface.

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1. Lying in a plane:

plane Cultural  

1. A geometrical location having only two dimensions — length and width (no height). (See coordinates and plane geometry.)

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Usage

What does plane mean? In geometry, a plane  is a flat, two-dimensional surface with an infinite height and width. It’s one of the basic concepts of geometry. Think of a flat sheet of paper. A physical sheet of paper has three dimensions: length, width, and (a small) height. If that sheet of paper had zero height and its length and width extended forever, it would be a plane. Obviously, such a shape is theoretical—it’s used as a basis for geometric calculations. A plane is one of several basic concepts students need to begin to understand geometry. Another is a point. Unlike a plane, it has no dimensions, such as length or width. It is found by using coordinates. A third concept is a line. Like a plane, a line also extends forever but only in two directions. Understanding what a plane is matters because angles and two-dimensional shapes, such as squares, triangles, and circles, are represented as points, lines, and line segments on a plane. It also helps you understand three-dimensional space and three-dimensional objects, which have height as well as length and width. Plane has several other meanings, some of which have different roots. More generally, it can refer to any flat or level surface.

Other Word Forms

• planeness
  noun

Etymology

Origin of plane¹

First recorded in 1400–50 plane ¹ ( for def. 9 ) (in the sense “to soar”); 1640–50 for noun and adjective senses; (noun) from Latin plānum “flat surface” (noun use of plānus “flat”); (adjective) from Latin plānus; first used to distinguish the geometrical senses formerly belonging to plain ¹; plane ¹ ( in def. 5 ), shortened form of airplane, aeroplane, or hydroplane; (verb) late Middle English planen “(of a bird) to soar” (compare Middle French planer ); akin to plain ¹

Origin of plane²

First recorded in 1375–1425; Middle English noun plane, plaine, pleine, from Middle French plan(n)e, Old French plaine, plane or directly from Late Latin plāna “plane, adze,” derivative of plānāre “to smooth,” itself derivative of Latin plānus plain ¹; Middle English verb plane(n), plaine, pleine, from Middle French planer or directly from Late Latin plānāre

Origin of plane³

First recorded in 1350–1400; Middle English plane, plaine, from Middle French plane, Old French pleine, plane, from Latin platanus, from Greek plátanos, derivative of platýs “wide, broad, flat” (with reference to the leaves)

Explanation

A plane is a vehicle that flies through the air, but it is also a tool used to make something smooth and flat, a kind of tree or a level surface. As a verb, to plane something is to make it flat and smooth. Don't confuse plane with plain, an adjective that means "simple" or a noun that means "flat land," like the plains of the American Midwest. This can be tricky because plane describes something that is flat and level, or the tool or action that makes something flat and level. If you remember that plain applies only to landforms, the difference will be plain to see — meaning obvious.

Example Sentences

See Examples For:

plane planed planing

A prominent Welsh businessman has been named as one of three people killed in a plane crash in the Swiss Alps.

From BBC ● Sep. 17, 2026

The lower the number, the more choice they have in which plane to fly, the higher their hourly compensation and the less risk of layoffs or furloughs.

From The Wall Street Journal ● Sep. 16, 2026

Police said Powers may have deliberately brought his plane down where he did to avoid kids playing softball nearby.

From Los Angeles Times ● Sep. 16, 2026

But two people familiar with the incident said a Saudi plane had been downed.

From The Wall Street Journal ● Sep. 16, 2026

“That whole plane thing did kind of ruin Angela’s life,” she said.

From "Found" by Margaret Peterson Haddix

Dale Hipkiss, from NH, said the top layer of the road surface had been planed away because of extensive damage caused by the spilled fuel.

From BBC ● Aug. 9, 2025

But if I could have a redo, I would have accepted the guide’s advice and planed for more time and mindless wandering in this special place among an already special southern Utah.

From Los Angeles Times ● Apr. 18, 2024

Every time we managed to summit a dune, following a sand ridge perfectly planed by the wind and sinking with each step, another beckoned us ahead.

From New York Times ● Feb. 27, 2023

Instead, the boards were gently removed, sent off to be de-nailed, cleaned, planed, and re-milled with tongue and grooves and then replaced.

From Seattle Times ● Jun. 14, 2022

A flock of pintail ducks planed down over the papyrus marsh and vanished among the reeds.

From "The Golden Goblet" by Eloise Jarvis McGraw

Garfield is goodness personified; we meet him on his farm, cooking breakfast for the family, planing wood to make a picnic table.

From Los Angeles Times ● Nov. 6, 2025

The proportion of businesses planing to raise prices fell five points to 49%.

From Reuters ● Jan. 11, 2022

On a wet morning in late October, the sound of electrical sanders whirring and the steady thunks of a craftsman planing a chair leg echoed through one of Century Furniture’s cavernous warehouses.

From New York Times ● Nov. 27, 2021

The firm processes the timber on three planing lines at the port run by 47 people.

From BBC ● Sep. 20, 2021

“They’ve put a planing mill on the eddy,” said Henry.

From "Go Set a Watchman: A Novel" by Harper Lee

Related Words

• airplane
• craft
• jet
• ship