# Nouns denoting two and three dimensional shapes

- acantha
- any sharply pointed projection
- acute angle
- an angle less than 90 degrees but more than 0 degrees
- acute triangle
- a triangle whose interior angles are all acute
- altitude
- the perpendicular distance from the base of a geometric figure to the opposite vertex (or side if parallel)
- amorphous shape
- an ill-defined or arbitrary shape
- anchor ring
- a toroidal shape
- angle
- the space between two lines or planes that intersect; the inclination of one line to another; measured in degrees or radians
- angle of attack
- the acute angle between the direction of the undisturbed relative wind and the chord of an airfoil
- angle of dip
- (physics) the angle that a magnetic needle makes with the plane of the horizon
- angle of extinction
- the angle from its axis that a crystal must be rotated before appearing maximally dark when viewed in polarized light
- angle of incidence
- the angle that a line makes with a line perpendicular to the surface at the point of incidence
- angle of inclination
- (geometry) the angle formed by the x-axis and a given line (measured counterclockwise from the positive half of the x-axis)
- angle of reflection
- the angle between a reflected ray and a line perpendicular to the reflecting surface at the point of incidence
- angle of refraction
- the angle between a refracted ray and a line perpendicular to the surface between the two media at the point of refraction
- angle of view
- the angle included by a photographic lens
- angular distance
- the angular separation between two objects as perceived by an observer
- angular shape
- a shape having one or more sharp angles
- arc
- a continuous portion of a circle
- arc
- something curved in shape
- arch
- a curved shape in the vertical plane that spans an opening
- articulation
- the shape or manner in which things come together and a connection is made
- asterism
- (mineralogy) a star-shaped figure with six rays that is seen in some crystal structures under reflected or transmitted light
- asymptote
- a straight line that is the limiting value of a curve; can be considered as tangent at infinity
- AZ
- the azimuth of a celestial body is the angle between the vertical plane containing it and the plane of the meridian
- balance
- equality of distribution
- ball
- an object with a spherical shape
- barrel
- a bulging cylindrical shape; hollow with flat ends
- base
- the bottom side of a geometric figure from which the altitude can be constructed
- bead
- a shape that is spherical and small
- bell
- the shape of a bell
- belly
- a part that bulges deeply
- bend
- an angular or rounded shape made by folding
- bend
- a circular segment of a curve
- bias
- a line or cut across a fabric that is not at right angles to a side of the fabric
- bifurcation
- the place where something divides into two branches
- bifurcation
- a bifurcating branch (one or both of them)
- bight
- a bend or curve (especially in a coastline)
- bight
- a loop in a rope
- blob
- an indistinct shapeless form
- block
- a three-dimensional shape with six square or rectangular sides
- bolus
- a small round soft mass (as of chewed food)
- border
- the boundary line or the area immediately inside the boundary
- bottleneck
- a narrowing that reduces the flow through a channel
- bound
- a line determining the limits of an area
- bowl
- a concave shape with an open top
- box
- a rectangular drawing
- brachium
- (biology) a branching or armlike part of an animal
- branch
- a part of a forked or branching shape
- brink
- a region marking a boundary
- buckle
- a shape distorted by twisting or folding
- bulb
- anything with a round shape resembling a teardrop
- bulge
- something that bulges out or is protuberant or projects from its surroundings
- camber
- a slight convexity (as of the surface of a road)
- caput
- a headlike protuberance on an organ or structure
- cardioid
- an epicycloid in which the rolling circle equals the fixed circle
- Cartesian plane
- a plane in which all points can be described in Cartesian coordinates
- cast
- the distinctive form in which a thing is made
- catenary
- the curve theoretically assumed by a perfectly flexible and inextensible cord of uniform density and cross section hanging freely from two fixed points
- cavity
- space that is surrounded by something
- center line
- a line that bisects a plane figure
- channel
- a long narrow furrow cut either by a natural process (such as erosion) or by a tool (as e.g. a groove in a phonograph record)
- chap
- a long narrow depression in a surface
- chord
- a straight line connecting two points on a curve
- circle
- something approximating the shape of a circle
- circle
- ellipse in which the two axes are of equal length; a plane curve generated by one point moving at a constant distance from a fixed point
- circlet
- a small circle
- cladogram
- a tree diagram used to illustrate phylogenetic relationships
- cleft
- a split or indentation in something (as the palate or chin)
- closed curve
- a curve (such as a circle) having no endpoints
- coil
- a round shape formed by a series of concentric circles (as formed by leaves or flower petals)
- columella
- a small column (or structure resembling a column) that is a part of a plant or animal
- column
- anything that approximates the shape of a column or tower
- complementary angles
- two angles whose sum is a right angle
- complex plane
- a geometric representation of the complex numbers established by the real axis and the orthogonal imaginary axis; it can be thought of as a modified Cartesian plane, with the real part of a complex number represented by a displacement along the x-axis, and the imaginary part by a displacement along the y-axis
- concave polygon
- a polygon such that there is a straight line that cuts it in four or more points
- concave polyhedron
- a polyhedron some of whose plane sections are concave polygons
- concave shape
- a shape that curves or bends inward
- cone
- a shape whose base is a circle and whose sides taper up to a point
- conformation
- a symmetrical arrangement of the parts of a thing
- conglobation
- a rounded spherical form
- conic
- (geometry) a curve generated by the intersection of a plane and a circular cone
- connection
- a connecting shape
- contortion
- a tortuous and twisted shape or position
- convex polygon
- a polygon such that no side extended cuts any other side or vertex; it can be cut by a straight line in at most two points
- convex polyhedron
- a polyhedron any plane section of which is a convex polygon
- convex shape
- a shape that curves or bulges outward
- convolution
- the shape of something rotating rapidly
- corner
- a small concavity
- corrugation
- a ridge on a corrugated surface
- crease
- a slight depression or fold in the smoothness of a surface
- crenation
- one of a series of rounded projections (or the notches between them) formed by curves along an edge (as the edge of a leaf or piece of cloth or the margin of a shell or a shriveled red blood cell observed in a hypertonic solution etc.)
- crescent
- any shape resembling the curved shape of the moon in its first or last quarters
- critical angle
- the smallest angle of incidence for which light is totally reflected
- crotch
- the region of the angle formed by the junction of two branches
- crotchet
- a sharp curve or crook; a shape resembling a hook
- crow's feet
- a wrinkle in the skin at the outer corner of your eyes
- cube
- a hexahedron with six equal squares as faces
- cuboid
- a rectangular parallelepiped
- cuneus
- any shape that is triangular in cross section
- cup
- any cup-shaped concavity
- Cupid's bow
- the double curve of the upper lip when considered to resemble Cupid's bow
- curtate cycloid
- a cycloid generated by a point inside the rolling circle
- curve
- the trace of a point whose direction of motion changes
- cutting angle
- the angle between the face of a cutting tool and the surface of the work
- cycloid
- a line generated by a point on a circle rolling along a straight line
- cylinder
- a surface generated by rotating a parallel line around a fixed line
- cylinder
- a solid bounded by a cylindrical surface and two parallel planes (the bases)
- decagon
- a polygon with 10 sides and 10 angles
- decahedron
- any polyhedron having ten plane faces
- delta
- an object shaped like an equilateral triangle
- dent
- a depression scratched or carved into a surface
- depression
- a concavity in a surface produced by pressing
- dermatoglyphic
- the lines that form patterns on the skin (especially on the fingertips and the palms of the hands and the soles of the feet)
- dewdrop
- a drop of dew
- diagonal
- (geometry) a straight line connecting any two vertices of a polygon that are not adjacent
- diameter
- a straight line connecting the center of a circle with two points on its perimeter (or the center of a sphere with two points on its surface)
- diamond
- a parallelogram with four equal sides; an oblique-angled equilateral parallelogram
- dimple
- any slight depression in a surface
- dip
- a depression in an otherwise level surface
- disc
- something with a round shape resembling a flat circular plate
- disproportion
- lack of proportion; imbalance among the parts of something
- distorted shape
- a shape resulting from distortion
- dodecagon
- a twelve-sided polygon
- dodecahedron
- any polyhedron having twelve plane faces
- dogleg
- angle that resembles the hind leg of a dog
- dome
- a concave shape whose distinguishing characteristic is that the concavity faces downward
- dot
- a very small circular shape
- double helix
- a pair of parallel helices intertwined about a common axis
- droop
- a shape that sags
- eccentricity
- (geometry) a ratio describing the shape of a conic section; the ratio of the distance between the foci to the length of the major axis
- element
- a straight line that generates a cylinder or cone
- element of a cone
- a straight line joining the apex and a point on the base
- element of a cylinder
- a straight line running the length of the cylinder
- ellipse
- a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it
- ellipsoid
- a surface whose plane sections are all ellipses or circles
- ellipsoid of revolution
- a shape that is generated by rotating an ellipse around one of its axes
- emptiness
- an empty area or space
- entasis
- a slight convexity in the shaft of a column; compensates for the illusion of concavity that viewers experience when the sides are perfectly straight
- envelope
- a curve that is tangent to each of a family of curves
- epicycle
- a circle that rolls around (inside or outside) another circle; generates an epicycloid or hypocycloid
- epicycloid
- a line generated by a point on a circle rolling around another circle
- equator
- a circle dividing a sphere or other surface into two usually equal and symmetrical parts
- equiangular triangle
- a three-sided regular polygon
- equilateral
- a figure whose sides are all equal
- exterior angle
- the supplement of an interior angle of a polygon
- extrados
- the exterior curve of an arch
- face angle
- the angle formed by two edges of a polyhedral angle
- facet
- a smooth surface (as of a bone or cut gemstone)
- facet plane
- the plane of a facet of an object (as of a cube)
- figure
- a combination of points and lines and planes that form a visible palpable shape
- figure 8
- a two-dimensionsal figure having the shape of the number eight
- flair
- a shape that spreads outward
- flank
- a subfigure consisting of a side of something
- forking
- the place where something divides into branches
- fossa
- a concavity in a surface (especially an anatomical depression)
- foursquare
- (geometry) a plane rectangle with four equal sides and four right angles; a four-sided regular polygon
- fringe
- the outside boundary or surface of something
- frown line
- a facial wrinkle associated with frowning
- frustum
- a truncated cone or pyramid; the part that is left when a cone or pyramid is cut by a plane parallel to the base and the apical part is removed
- funnel
- a conical shape with a wider and a narrower opening at the two ends
- geodesic
- (mathematics) the shortest line between two points on a mathematically defined surface (as a straight line on a plane or an arc of a great circle on a sphere)
- gnarl
- something twisted and tight and swollen
- gooseneck
- something in a thin curved form (like the neck of a goose)
- HA
- (astronomy) the angular distance of a celestial point measured westward along the celestial equator from the zenith crossing; the right ascension for an observer at a particular location and time of day
- heart
- a plane figure with rounded sides curving inward at the top and intersecting at the bottom; conventionally used on playing cards and valentines
- heart line
- a crease on the palm; palmists say it indicates your emotional nature
- helix angle
- the constant angle at which a helix cuts the elements of a cylinder or cone
- helix
- a curve that lies on the surface of a cylinder or cone and cuts the element at a constant angle
- hemicycle
- a plane figure with the shape of half a circle
- hemisphere
- half of a sphere
- heptagon
- a seven-sided polygon
- hexagon
- a six-sided polygon
- hexagram
- a regular polygon formed by extending each of the sides of a regular hexagon to form two equilateral triangles
- hexahedron
- any polyhedron having six plane faces
- hip
- (architecture) the exterior angle formed by the junction of a sloping side and a sloping end of a roof
- hole
- an unoccupied space
- hollow
- a cavity or space in something
- hoodoo
- (geology) a column of weathered and unusually shaped rock
- hyperbola
- an open curve formed by a plane that cuts the base of a right circular cone
- hyperboloid
- a quadric surface generated by rotating a hyperbola around its main axis
- hypocycloid
- a line generated by a point on a circle that rolls around inside another circle
- hypotenuse
- the side of a right triangle opposite the right angle
- icosahedron
- any polyhedron having twenty plane faces
- incisura
- (anatomy) a notch or small hollow
- inclination
- (astronomy) the angle between the plane of the orbit and the plane of the ecliptic stated in degrees
- indentation
- a concave cut into a surface or edge (as in a coastline)
- interior angle
- the angle inside two adjacent sides of a polygon
- intersection
- a point or set of points common to two or more geometric configurations
- intrados
- the interior curve of an arch
- isogon
- an equiangular polygon
- isosceles triangle
- a triangle with two equal sides
- jog
- a sharp change in direction
- Jordan curve
- a closed curve that does not intersect itself
- keel
- a projection or ridge that suggests a keel
- kink
- a sharp bend in a line produced when a line having a loop is pulled tight
- knife
- any long thin projection that is transient
- knob
- any thickened enlargement
- lead
- the angle between the direction a gun is aimed and the position of a moving target (correcting for the flight time of the missile)
- leaf form
- any of the various shape that leaves of plants can assume
- lemniscate
- any of several plane algebraic curves in the shape of a figure eight
- life line
- a crease on the palm; its length is said by palmists to indicate how long you will live
- line
- a length (straight or curved) without breadth or thickness; the trace of a moving point
- line of Saturn
- a crease on the palm; palmists say it indicates how successful you will be
- line roulette
- a line generated by a point on one figure rolling around a second figure
- loop
- anything with a round or oval shape (formed by a curve that is closed and does not intersect itself)
- lower bound
- (mathematics) a number equal to or less than any other number in a given set
- magnetic declination
- the angle (at a particular location) between magnetic north and true north
- midline
- the median plane of the body (or some part of the body)
- mogul
- a bump on a ski slope
- natural shape
- a shape created by natural forces; not man-made
- node
- a connecting point at which several lines come together
- nonagon
- a nine-sided polygon
- notch
- a V-shaped indentation
- nub
- a small lump or protuberance
- oblique angle
- an angle that is not a right angle or a multiple of a right angle
- oblique triangle
- a triangle that contains no right angle
- oblong
- a plane figure that deviates from a square or circle due to elongation
- obtuse angle
- an angle between 90 and 180 degrees
- obtuse triangle
- a triangle that contains an obtuse interior angle
- octagon
- an eight-sided polygon
- octahedron
- any polyhedron having eight plane faces
- orbital plane
- (astronomy) the plane on which a body is orbiting
- ovoid
- an egg-shaped object
- parabola
- a plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the curve
- paraboloid
- a surface having parabolic sections parallel to a single coordinate axis and elliptic sections perpendicular to that axis
- parallel
- (mathematics) one of a set of parallel geometric figures (parallel lines or planes)
- parallelepiped
- a prism whose bases are parallelograms
- parallelogram
- a quadrilateral whose opposite sides are both parallel and equal in length
- peak
- a V shape
- pellet
- a small sphere
- pencil
- a figure formed by a set of straight lines or light rays meeting at a point
- pentacle
- a star with 5 points; formed by 5 straight lines between the vertices of a pentagon and enclosing another pentagon
- pentagon
- a five-sided polygon
- pentahedron
- any polyhedron having five plane faces
- perigon
- an angle of 360 degrees
- perimeter
- a line enclosing a plane areas
- perpendicular
- a straight line at right angles to another line
- perversion
- a curve that reverses the direction of something
- 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
- pipe
- a hollow cylindrical shape
- plane angle
- an angle formed by two straight lines (in the same plane)
- plane figure
- a two-dimensional shape
- plane
- (mathematics) an unbounded two-dimensional shape
- Platonic solid
- any one of five solids whose faces are congruent regular polygons and whose polyhedral angles are all congruent
- plume
- anything that resembles a feather in shape or lightness
- (bowling) the space between the headpin and the pins behind it on the right or left
- an enclosed space
- a hollow concave shape made by removing something
- polygon
- a closed plane figure bounded by straight sides
- polyhedral angle
- the space enclosed by three or more planes that intersect in a vertex
- polyhedron
- a solid figure bounded by plane polygons or faces
- pore
- any tiny hole admitting passage of a liquid (fluid or gas)
- prism
- a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms
- prismatoid
- a polyhedron whose vertices all lie in one or the other of two parallel planes; the faces that lie in those planes are the bases of the prismatoid
- prismoid
- a prismatoid whose bases are polygons having the same number of sides and whose other faces are trapezoids or parallelograms
- projection
- any solid convex shape that juts out from something
- prolate cycloid
- a cycloid generated by a point outside the rolling circle
- proportion
- balance among the parts of something
- pucker
- an irregular fold in an otherwise even surface (as in cloth)
- pyramid
- a polyhedron having a polygonal base and triangular sides with a common vertex
- quadrangle
- a four-sided polygon
- quadrangular prism
- a prism whose bases are quadrangles
- quadrate
- a square-shaped object
- quadrate
- a cubelike object
- quadric
- a curve or surface whose equation (in Cartesian coordinates) is of the second degree
- radius
- a straight line from the center to the perimeter of a circle (or from the center to the surface of a sphere)
- ray
- (mathematics) a straight line extending from a point
- rectangle
- a parallelogram with four right angles
- reentering angle
- an interior angle of a polygon that is greater than 180 degrees
- reentering polygon
- a polygon with one or more reentrant angles
- reflex angle
- an angle greater than 180 degrees (but less than 360)
- regular dodecahedron
- a dodecahedron with twelve regular pentagons as faces
- regular hexagon
- a hexagon with six sides of equal length
- regular icosahedron
- an icosahedron with twenty equilateral triangles as faces
- regular octahedron
- an octahedron with eight equilateral triangles as faces
- regular polygon
- a polygon with all sides and all angles equal
- regular tetrahedron
- a tetrahedron with four equilateral triangular faces
- rhombohedron
- a parallelepiped bounded by six similar faces (either rhombuses or parallelograms)
- rhomboid
- a parallelogram with adjacent sides of unequal lengths; an oblique-angled parallelogram with only the opposite sides equal
- ridge
- any long raised strip
- right angle
- the 90 degree angle between two perpendicular lines
- right triangle
- a triangle with one right angle
- rim
- the shape of a raised edge of a more or less circular object
- round shape
- a shape that is curved and without sharp angles
- rut
- a groove or furrow (especially one in soft earth caused by wheels)
- S-shape
- a double curve resembling the letter S
- salient angle
- an angle pointing outward; an interior angle of a polygon that is less than 180 degrees
- scalene triangle
- a triangle with no two sides of equal length
- score
- a slight surface cut (especially a notch that is made to keep a tally)
- secant
- a straight line that intersects a curve at two or more points
- sector
- a plane figure bounded by two radii and the included arc of a circle
- shapelessness
- an amorphous or indefinite shape
- sine curve
- the curve of y=sin x
- sinuosity
- having curves
- snag
- a sharp protuberance
- solid
- a three-dimensional shape
- solid angle
- an angle formed by three or more planes intersecting at a common point (the vertex)
- solid figure
- a three-dimensional shape
- space
- an empty area (usually bounded in some way between things)
- sphere
- a three-dimensional closed surface such that every point on the surface is equidistant from the center
- sphere
- a solid figure bounded by a spherical surface (including the space it encloses)
- spherical angle
- an angle formed at the intersection of the arcs of two great circles
- spherical polygon
- a figure on the surface of a sphere bounded by arcs of 3 or more great circles
- spherical triangle
- a spherical polygon formed by the arcs of 3 great circles
- spherule
- a small sphere
- spiral
- a plane curve traced by a point circling about the center but at increasing distances from the center
- square
- something approximating the shape of a square
- star
- a plane figure with 5 or more points; often used as an emblem
- stemma
- a tree diagram showing a reconstruction of the transmission of manuscripts of a literary work
- straight line
- a line traced by a point traveling in a constant direction; a line of zero curvature
- stria
- any of a number of tiny parallel grooves such as: the scratches left by a glacier on rocks or the streaks or ridges in muscle tissue
- subfigure
- a figure that is a part of another figure
- tail
- any projection that resembles the tail of an animal
- tangent
- a straight line or plane that touches a curve or curved surface at a point but does not intersect it at that point
- tangent plane
- the plane that contains all the lines tangent to a specific point on a surface
- taper
- a convex shape that narrows toward a point
- teardrop
- anything shaped like a falling drop (as a pendant gem on an earring)
- tesseract
- the four-dimensional analogue of a cube
- tetrahedron
- any polyhedron having four plane faces
- thalweg
- the middle of the chief navigable channel of a waterway that forms the boundary line between states
- tilt angle
- the angle a rocket makes with the vertical as it curves along its trajectory
- toroid
- the doughnut-shaped object enclosed by a torus
- toroid
- a ring-shaped surface generated by rotating a circle around an axis that does not intersect the circle
- trapezium
- a quadrilateral with no parallel sides
- trapezohedron
- a polyhedron whose faces are trapeziums
- trapezoid
- a quadrilateral with two parallel sides
- tree
- a figure that branches from a single root
- triangle
- something approximating the shape of a triangle
- triangle
- a three-sided polygon
- triangular prism
- a prism whose bases are triangles
- true anomaly
- the angular distance of a point in an orbit past the point of periapsis measured in degrees
- truncated cone
- a frustum formed from a cone
- truncated pyramid
- a frustum formed from a pyramid
- uncus
- (biology) any hook-shaped process or part
- undecagon
- an eleven-sided polygon
- undulation
- an undulating curve
- upper bound
- (mathematics) a number equal to or greater than any other number in a given set
- vector
- a straight line segment whose length is magnitude and whose orientation in space is direction
- vertical angle
- either of two equal and opposite angles formed by the intersection of two straight lines
- verticil
- a whorl of leaves growing around a stem
- wart
- any small rounded protuberance (as on certain plants or animals)
- washout
- the channel or break produced by erosion of relatively soft soil by water
- wave angle
- the angle of arrival (or departure) of a radio wave with respect to the axis of an antenna array
- zag
- an angular shape characterized by sharp turns in alternating directions