The following list covers the most common words for shapes in the English language, with explanations (sorry, no pictures!). Words that may be also be useful when discussing different shapes are side (the edge of the shape), face (the surface of a shape), regular (all sides the same length) and irregular (sides with different lengths), and 3D (when shapes have a third-dimension (3D), or depth – 2D shapes are flat).
Common Shape Vocabulary
This part of the list covers the more common everyday shape words you might encounter.
arc – a curve, a segment of a circle
circle – one regular round line
cone – 3D shape from a flat base to a single high point (tapers)
crescent – a curved line, like a moon
cube – 3D shape made of 6 equal sized squares
cuboid – 3D shape made of 6 rectangles
curve – a line that is not straight
cylinder – 3D shape joining two circular bases
disc – flat 3D circle
dot – a single point
ellipse – an irregular (not symmetrical) circle
heptagon – 7 sided shape
hexagon – 6 sided shape
kite – diamond shape
line – connects two points
octagon – 8 sided shape
orb – a sphere
oval – an egg shape
parallelogram – a shape with two sets of parallel sides
pentagon – 5 sided shape
plane – a surface
point – a specific place
polygon – a shape with lines that connect to form one complete space
prism – a type of polyhedron
pyramid – 3D shape with triangular faces
ray – a part of a line that is finite in one direction
rectangle – 4 sided shape with 2 sets of different length lines
rhombus – 4 sided shape with equal length sides
ring – a circular shape
semicircle – half a circle
shape – an object located in a defined space
shapeless – something without a defined space
sphere – a perfectly round 3D shape
square – 4 sided shape with equal length sides and 90 degree angles
star – a shape with many points
trapezium (UK) / trapezoid (US) – a 4 sided shape with only 2 parallel sides
triangle – 3 sided shape
wedge – a triangular prism
More Shape Words
The following terms are less common, or more specific, words for shapes, which may also be useful to learn.
acute triangle – triangle with all angles less than 90 degrees
annulus – a ring
bipyramid – a polyhedron of two pyramids
concave – an outward curve
convex – an inward curve
decagon – a 10 sided shape
dodecahedron – 3D shape with 12 faces
ellipsoid – 3D ellipse
equilateral triangle – triangle with all angles equal
helix – 3D curve
hexahedron – 3D shape with 7 faces
isosceles triangle – triangle with two equal angles
lozenge – a diamond shape
obtuse triangle – triangle with an angle more than 90 degrees
octahedron – 3D shape made of 8 faces
polyhedron – a 3D shape with numerous flat faces
right triangle – a triangle with one angle that is 90 degrees
scalene triangle – a triangle where all sides are unequal
