Unlike a regular shape, an irregular shape is a polygon with sides that aren't all equal and unequal angles. Some conventional geometric shapes, such as the rectangle, parallelogram and rhombus, are irregular. A rectangle has four 90 degree angles, but its sides aren't all the same length. A rhombus and parallelogram both have four equal sides, but they each have two inward angles and two outward angles.

Like the rectangle, rhombus and parallelogram, the trapezoid and kite are irregular quadrilaterals. A trapezoid has four different side lengths and four different angles. A traditional kite shape has two different pairs of matching sides and just one pair of matching angles.

An equilateral triangle is regular, but all other common triangles are irregular. The isosceles triangle has two equal sides and two equal angles. A scalene triangle has no equal sides and no equal angles.

Many other shapes that people see on everyday objects are irregular, though they may not have standard geometric names. Home plate in baseball is an irregular pentagon. It has three sides that are equal and three angles that are equal, but the top part of the plate forms a triangle shape. A two-dimensional arrow symbol and a two-dimensional lightning bolt are both irregular shapes.