plane
Pluralplanes
Pluralplanes
- 1A powered aircraft with fixed wings; an airplane.
The plane climbed steeply after leaving the runway.
Heavy snow grounded every plane at the regional airport.
UsageTravel by plane (no the) or on a plane. You get on, board or catch a plane.
Similaraircraft, airplane, aeroplane, jet
Note
A clipping of aeroplane, and the short form is handy because it avoids choosing between the spellings airplane and aeroplane. It is the everyday word on both sides of the Atlantic, in phrases such as plane ticket and plane crash.
- 2A flat surface, often imaginary, extending in all directions, or a bounded part of one, such as a plane in geometry or one used to divide the body into sections.
Any three points that are not in a line define a single plane.
The two planes intersect along a straight line.
Note
Geometry's plane has no edge and no thickness. Any three points not in a line fix exactly one, and two planes that are not parallel meet along a straight line. Outside pure mathematics it usually means a bounded piece named by its orientation, the horizontal or vertical plane. Graham Burtenshaw and Michael S. Welch, writing in 1979 on Bulleid's railway coaches, describe mirrors "canted out of the vertical plane" to cut reflections.
Checked 1 Nov 2026 · 5 facts
- A geometrical plane extends indefinitely and has no thickness. openstax.org
- Three noncollinear points determine exactly one plane. jwilson.coe.uga.edu
- Nonparallel planes intersect along a straight line in Euclidean three-dimensional space. mathworld.wolfram.com
- Graham Burtenshaw and Michael S. Welch wrote about Bulleid's coaches in 1979. en.wiktionary.org
- The authors describe tilted mirrors using the exact quoted words and give reducing reflections as the purpose. en.wiktionary.org
- 3
- 4A particular level at which something exists or has developed.
The artist's later work operates on an entirely different plane.
They spoke of spirits existing on a higher plane.
UsageUsually on a ... plane: on a higher plane, on a different plane.
Similarlevel, dimension, realm, sphere
Note
In spiritual writing, the astral plane names a realm beyond the physical. In criticism the word sets something apart, often as praise: a performance on another plane is one that leaves ordinary work far behind.
Less common meanings
- 5Of a surface, lying perfectly flat and level throughout.
The lens must sit against a perfectly plane surface.
Engineers checked that the mirror was truly plane.
UsageNot the same as plain: a plane surface is flat, while a plain one is simple or undecorated.
Similarflat, level, even, planar
Note
The spelling exists to keep geometry apart from everyday speech. Latin plānus also gave English plain, and in the 17th century plane was introduced so that the geometrical senses had a form of their own. The adjective keeps that exact, measured feel: a plane surface or a plane mirror is truly flat, while plain kept the word's other meanings.
Checked 1 Nov 2026 · 2 facts
- The spelling plane was introduced in the 17th century to distinguish geometrical senses from the other senses of plain. en.wiktionary.org
- English plain derives ultimately from Latin plānus. en.wiktionary.org
- 6A woodworking tool with a blade that pares fine shavings from a surface, leaving it smooth and even.
She sharpened the plane before flattening the tabletop.
A few passes with the plane left the surface glass-smooth.
Note
A separate word from the geometer's plane, though both reach back to Latin. The tool pairs a flat sole with an angled blade that pares off thin shavings.
Checked 2 Nov 2026 · 1 fact
- A woodworking plane combines a flat sole with an angled blade that removes thin shavings. en.wikipedia.org
- 7
- 8
- 9Of a boat, to travel fast enough that the hull rises and skims along the surface instead of pushing through the water.
With the throttle open, the hull started to plane over the flat water.
Lightweight skiffs plane more easily than heavy cruisers.
Similarskim
Note
Here speed does the lifting. As a boat goes faster, the water begins to carry the hull instead of the hull pushing through it, so the hull lifts higher in the water and drag eases. Boaters contrast planing with displacement running, and they say a light hull planes easily where a heavy cruiser struggles. The subject is a boat or a board: a skiff planes over flat water.
- 10A roughly flat, thin, often movable structure that creates sideways force from air or water flowing over it, used on aircraft, submarines, and similar craft.
The submarine's forward planes angled downward to begin the descent.
Each plane adjusts slightly to steer the craft through the water.
- 11A broad-leaved deciduous tree of the genus Platanus.
The old plane by the canal sheds strips of bark every summer.
The planes along the river drop their leaves early.
Similarsycamore
- 12A sycamore tree.
- 13Any of 17 designated ranges of 65,536 sequential code points each, used to organize Unicode characters.
- 14Any of several butterflies of Asia and Australasia known as planes, including species from two different families, many of which fly with a slow, gliding motion.
Showing meanings only.
Practice
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Origins
Latin plānus ("plain") had a neuter form used as a noun, plānum ("flat surface"), and that is the source. English adopted it in the 17th century to keep the geometry senses separate from plain's other meanings. Llano, piano, and plain are doublets.
Late Latin plāna ("planing tool") became Anglo-Norman plaine, which gave Middle English plane or plaine.
A clipping of "aeroplane."
Checked 1 Nov 2026 · 1 fact
- Plane originated as a clipping of aeroplane. en.wiktionary.org
The traditional explanation links Ancient Greek πλάτανος (plátanos) to πλατύς (platús, "wide, broad"), but this derivation is disputed. Latin borrowed the tree name as platanus. It passed into Old French as plane, which Middle English borrowed as plane.