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.

Primary Meanings of plane

(mathematics) an unbounded two-dimensional shape
a level of existence or development
an aircraft that has a fixed wing and is powered by propellers or jets
travel on the surface of water
a carpenter's hand tool with an adjustable blade for smoothing or shaping wood
cut or remove with or as if with a plane
having a surface without slope, tilt in which no part is higher or lower than another
Full Definitions of plane

n (mathematics) an unbounded two-dimensional shape

“we will refer to the plane of the graph as the X-Y plane”
“any line joining two points on a plane lies wholly on that plane”
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Cartesian plane
a plane in which all points can be described in Cartesian coordinates
facet plane
the plane of a facet of an object (as of a cube)
midline, midplane
the median plane of the body (or some part of the body)
orbital plane
(astronomy) the plane on which a body is orbiting
picture plane
the plane that is in the foreground of a drawing or painting; coextensive with but different from the objective surface of the work
tangent plane
the plane that contains all the lines tangent to a specific point on a surface
Type of:
form, shape
the spatial arrangement of something as distinct from its substance

n a level of existence or development

“he lived on a worldly plane
Type of:
degree, level, point, stage
a specific identifiable position in a continuum or series or especially in a process

n an aircraft that has a fixed wing and is powered by propellers or jets

aeroplane, airplane
United States military aircraft; B- stands for bomber
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a commercial airplane that carries passengers
amphibian, amphibious aircraft
an airplane designed to take off and land on water
old fashioned airplane; has two wings one above the other
a military aircraft that drops bombs during flight
delta wing
an airplane with wings that give it the appearance of an isosceles triangle
attack aircraft, fighter, fighter aircraft
a high-speed military or naval airplane designed to destroy enemy aircraft in the air
hangar queen
an airplane with a bad maintenance record
jet, jet plane, jet-propelled plane
an airplane powered by one or more jet engines
an airplane with a single wing
multiengine airplane, multiengine plane
a plane with two or more engines
propeller plane
an airplane that is driven by a propeller
reconnaissance plane
a military airplane used to gain information about an enemy
hydroplane, seaplane
an airplane that can land on or take off from water
an airplane equipped with skis so it can land on a snowfield
tanker plane
an airplane constructed to transport chemicals that can be dropped in order to fight a forest fire
a subsonic jet airliner operated over short distances
dive bomber
a bomber that releases its bombs during a steep dive toward the target
double-prop, double-propeller plane, twin-prop, twin-propeller-plane
a propeller plane with an engine that drives two propellers in opposite directions (for stability)
fan-jet, fanjet, turbofan, turbojet
an airplane propelled by a fanjet engine
floatplane, pontoon plane
a seaplane equipped with pontoons for landing or taking off from water
flying boat
a large seaplane that floats with its fuselage in the water rather than on pontoons
a fast maneuverable fighter plane designed to intercept enemy aircraft
a large jet plane that carries passengers
jumbo jet, jumbojet
a very large jet plane
a fighter plane used for suicide missions by Japanese pilots in World War II
narrow-body, narrow-body aircraft, narrowbody aircraft
a commercial airliner with a single aisle
propjet, turbo-propeller plane, turboprop
an airplane with an external propeller that is driven by a turbojet engine
single prop, single-propeller plane
a propeller plane with a single propeller
stealth bomber
a bomber that is difficult to detect by radar
stealth fighter
a fighter that is difficult to detect by radar; is built for precise targeting and uses laser-guided bombs
a jet plane propelled by two jet engines
twin-aisle airplane, wide-body, wide-body aircraft, widebody aircraft
a commercial airliner with two aisles
Type of:
heavier-than-air craft
a non-buoyant aircraft that requires a source of power to hold it aloft and to propel it

v travel on the surface of water

ride on an aquaplane
rise up onto a thin film of water between the tires and road so that there is no more contact with the road
Type of:
move smoothly and effortlessly

n a carpenter's hand tool with an adjustable blade for smoothing or shaping wood

“the cabinetmaker used a plane for the finish work”
carpenter's plane, woodworking plane
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beading plane
a plane with a concave blade for making moulding with beadwork
block plane
a small plane used on end grains of wood
bullnose, bullnosed plane
a small carpenter's plane with the cutting edge near the front
chamfer plane
a plane that makes a beveled edge
circular plane, compass plane
a plane with a flexible face that can plane concave or convex surfaces
combination plane
a woodworking plane that has interchangeable cutters of various shapes
dovetail plane
a woodworking plane designed to make the grooves for dovetail joints
fore plane
a carpenter's plane intermediate between a jack plane and a jointer plane
jack plane
a carpenter's plane for rough finishing
jointer, jointer plane, jointing plane, long plane
a long carpenter's plane used to shape the edges of boards so they will fit together
match plane, tonguing and grooving plane
a plane having cutters designed to make the tongues and grooves on the edges of matchboards
openside plane, rabbet plane
a woodworking plane designed to cut rabbets
router plane
a woodworking plane with a narrow cutting head that will make grooves with smooth bottoms
scrub plane
a narrow woodworking plane used to cut away excess stock
smooth plane, smoothing plane
a small plane for finish work
a small plane that has a handle on each side of its blade; used for shaping or smoothing cylindrical wooden surfaces (originally wheel spokes)
dado plane
a plane for making a dado groove
Type of:
edge tool
any cutting tool with a sharp cutting edge (as a chisel or knife or plane or gouge)
hand tool
a tool used with workers' hands

n a power tool for smoothing or shaping wood

planer, planing machine
Type of:
power tool
a tool driven by a motor

v cut or remove with or as if with a plane

Type of:
separate with or as if with an instrument

v make even or smooth, with or as with a carpenter's plane

plane the top of the door”
Type of:
smooth, smoothen
make smooth or smoother, as if by rubbing

adj having a surface without slope, tilt in which no part is higher or lower than another

“a plane surface”
flat, level
being level or straight or regular and without variation as e.g. in shape or texture; or being in the same plane or at the same height as something else (i.e. even with)