Shapes Vocabulary: Different Shape Names

August 3, 2023

From pencils and paper to wheels, shapes are everywhere. But how well are you familiar with geometry? In this article, you’ll discover different kinds of shapes, from circles to polygons.

Table of Contents

What Are Shapes?

Shapes are any object you can characterize by its number of sides, angles, outlines, and symmetry. They can be categorized into various types, including circles, triangles, squares, rectangles, and polygons.

What Are the Different Types of Shapes?

As mentioned earlier, you’ll come across different shapes, but in general, they are divided into two main categories: two-dimensional and three-dimensional.

Two-Dimensional (Flat) Shapes

Photo showing the different 2D shape names

If you draw any shape on a sheet of paper, that figure is two-dimensional, which means it exists solely on a flat surface. You can’t physically hold the drawn shape without gripping the paper. In short, the dimensions of 2D shapes have length and width but lack depth or volume.

Triangles

One of the most well-known 2D shapes is the triangle. This figure has three lines that connect at their endpoints. The sum of these angles in any triangle always totals 180 degrees.

Acute Triangle: When a triangle’s three angles measure less than 90 degrees, you’ll call it an acute triangle.
Right Triangle: If you’ve heard of the Pythagorean Theorem in mathematics, then you probably know what a right triangle is. If it’s your first time hearing it, don’t worry, it is easy! As its name suggests, a right triangle only has one right angle, which measures exactly 90 degrees.
Obtuse Triangle: What if one of the triangle’s angles is more than 90 degrees? It is called an obtuse triangle, which directly contrasts acute triangles.
Equilateral Triangle: Now, if a triangle’s three sides share equal angles, you will call it an equilateral triangle.
Isosceles Triangle: But what if only two sides of equal length and the angles opposite those equal sides are also identical? These are called isosceles triangles.
Scalene Triangle: Scalene triangles are the free spirits of the triangle family. All three sides are of different lengths.

Quadrilaterals

Photo showing different shapes under the quadrilateral category.

If a shape has four sides, they are not triangles; they are quadrilaterals. But just like triangles, quadrilaterals are divided into different types:

Square: One of the most popular quadrilaterals is square. Unlike other types, you will notice that all of its four sides have the same length and 90 degrees angles.
Rectangle: Many people confuse square and rectangle. If you are one of them, just remember that a rectangle features pairs of opposite sides of equal measurements. For instance, on its left, it measures 4 inches, so that means its opposite side (the right) is 4 inches too, whereas the top (let’s say 10 inches) share the same length as the bottom. If you have a square, all sides (left, right, top, and bottom) should be 4 inches. Another fun fact is that all the sides of a rectangle are right angles (90 degrees).
Parallelogram: Don’t be confused with parallelograms – they still fall under the quadrilateral category! Unlike squares and rectangles, a parallelogram, as its name suggests, features two pairs of opposite angles that are congruent.
Rhombus: Rhombus’ defining feature is that opposite sides are parallel, and opposite angles are congruent. You should also keep in mind that its vertices form a diamond-like shape.
Trapezium (Trapezoid): As for trapezoids, you will also notice that it has one pair of parallel sides. But unlike the parallelogram, its parallel sides have unequal lengths.
Kite: This quadrilateral resembles a diamond because its two pairs of adjacent sides share the same length. Keep in mind, though. It features one pair of congruent, opposite angles, while the other pair of opposite angles is non-congruent.

Circle

We’re all familiar with a circle – a shape free of any edges or corners. You can describe it as a single continuous curve equidistant from its center point. Another fun fact is that circles have infinite points along their circumference.

Oval

So, what about ovals? One way to distinguish ovals from circles is that they are stretched out. However, like circles, they don’t have corners or edges. Eggs and certain fruits are oval-shaped.

Polygons

The most distinct feature of any polygon (whether a five-sided pentagon or a nine-sided nonagon) is its straight sides. You can classify polygons based on the number of their sides.

Pentagon: As teased earlier, when a polygon has five sides (as well as five angles and five vertices), it is called a pentagon.
Hexagon: What if the shape has six sides? In that case, it’s a hexagon.
Heptagon: For polygon shapes with seven sides, it’s a heptagon.
Octagon: If there are eight sides, you will call it an octagon. Fun fact: This shape’s name is derived from the word “octo,” meaning eight.
Nonagon: For nonagons, you will get nine sides.

Three-Dimensional Shapes

Photo showing different types of 3D shapes

With three-dimensional (3D) shapes, you will notice that they are not confined to a flat surface. They have length, width, height, and depth, allowing you to view the shape from multiple angles. And just like 2D shapes, a three-dimensional object is divided into different types:

Polyhedra

First up is the polyhedra. This 3D geometric figure has three distinct features: flat faces, straight edges, and sharp corners. They also have distinct angles formed by the intersection of their faces and are defined by their vertices, where the edges meet.

Cube: You can identify a cube by its six congruent square faces, where each face meets at a right angle. It has eight vertices and twelve edges, creating a symmetrical and regular structure.
Cuboid: Don’t confuse a cuboid with a cube. Although it has six faces, they are rectangular, and the opposite faces are congruent and parallel. Cuboids often represent everyday objects like boxes or rectangular prisms.
Pyramid: For pyramids, they have polygonal bases and triangular faces that converge to a single point called the apex. You can identify the type of pyramid by looking at the shape of the base.

Spheres

Another popular type of 3D shape is the sphere. This shape is perfectly symmetrical because it has no edges or corners. Think of it like a circle but something you can hold in your hands, like a round ball or a globe.

Cylinders

Soda cans, water bottles, and a paint bucket can. What do they have in common? Well, they fall under the geometrical shape cylinders. As you might have guessed, this shape has two congruent circular bases connected by a curved surface.

Cylinders are divided into two types:

Right Cylinder: Most cans and bottles are considered a right cylinder because their two parallel circular bases share the same size and shape. Moreover, you’ll notice that their lateral surface is perpendicular to the planes of the bases and has a constant radius.
Oblique Cylinder: Unlike a right cylinder, the lateral surface of an oblique cylinder is slanted or tilte.

Cones

From traffic cones and birthday hats to ice cream cones, these everyday objects, as you might have guessed, has a cone shape. This 3D figure features a circular base and curved lateral surfaces that converge towards the top, forming the apex.

Just like cylinders, there are two types of cones:

Right Cone: Popular cone-shaped objects are right cones, which means their apex is directly above the circular base’s center.
Oblique Cone: As you might have guessed, an oblique cone’s apex is not perpendicular to the base’s center.

Different Shape Names

From the simplicity of squares and circles to the intriguing complexity of trapezoids and hexagons, there are different shape names that you should be familiar with: